diff --git a/src/OpenFOAM/db/IOstreams/IOstreams/IOstream.C b/src/OpenFOAM/db/IOstreams/IOstreams/IOstream.C
index a627e382bf..eba797a2bc 100644
--- a/src/OpenFOAM/db/IOstreams/IOstreams/IOstream.C
+++ b/src/OpenFOAM/db/IOstreams/IOstreams/IOstream.C
@@ -35,6 +35,27 @@ License
 Foam::fileName Foam::IOstream::staticName_("stream");
 
 
+// * * * * * * * * * * * * Protected Member Functions  * * * * * * * * * * * //
+
+void Foam::IOstream::attach(const std::ios& s)
+{
+    labelByteSize_ = sizeof(label);
+    scalarByteSize_ = sizeof(scalar);
+    lineNumber_ = 0;
+
+    if (s.good())
+    {
+        setOpened();
+        setGood();
+    }
+    else
+    {
+        setClosed();
+        setState(s.rdstate());
+    }
+}
+
+
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
 const Foam::fileName& Foam::IOstream::name() const
diff --git a/src/OpenFOAM/db/IOstreams/IOstreams/IOstream.H b/src/OpenFOAM/db/IOstreams/IOstreams/IOstream.H
index b05e073cb3..270e373ed6 100644
--- a/src/OpenFOAM/db/IOstreams/IOstreams/IOstream.H
+++ b/src/OpenFOAM/db/IOstreams/IOstreams/IOstream.H
@@ -157,6 +157,9 @@ protected:
             ioState_ = std::ios_base::goodbit;
         }
 
+        //- Adjustments when attaching a new stream
+        void attach(const std::ios& s);
+
 
 public:
 
diff --git a/src/OpenFOAM/db/IOstreams/Sstreams/ISstream.C b/src/OpenFOAM/db/IOstreams/Sstreams/ISstream.C
index 7aa75ebd92..9ade46c888 100644
--- a/src/OpenFOAM/db/IOstreams/Sstreams/ISstream.C
+++ b/src/OpenFOAM/db/IOstreams/Sstreams/ISstream.C
@@ -723,7 +723,7 @@ Foam::Istream& Foam::ISstream::read(token& t)
             // readScalar determine the validity
             while
             (
-                is_.get(c)
+                is_->get(c)
              && (
                     isdigit(c)
                  || c == '+'
@@ -758,13 +758,13 @@ Foam::Istream& Foam::ISstream::read(token& t)
 
             syncState();
 
-            if (is_.bad())
+            if (is_->bad())
             {
                 t.setBad();
             }
             else
             {
-                is_.putback(c);
+                is_->putback(c);
 
                 if (nChar == 1 && buf[0] == '-')
                 {
@@ -1009,7 +1009,7 @@ Foam::Istream& Foam::ISstream::read(string& str)
 
 Foam::Istream& Foam::ISstream::read(label& val)
 {
-    is_ >> val;
+    (*is_) >> val;
     syncState();
     return *this;
 }
@@ -1017,7 +1017,7 @@ Foam::Istream& Foam::ISstream::read(label& val)
 
 Foam::Istream& Foam::ISstream::read(float& val)
 {
-    is_ >> val;
+    (*is_) >> val;
     syncState();
     return *this;
 }
@@ -1025,7 +1025,7 @@ Foam::Istream& Foam::ISstream::read(float& val)
 
 Foam::Istream& Foam::ISstream::read(double& val)
 {
-    is_ >> val;
+    (*is_) >> val;
     syncState();
     return *this;
 }
@@ -1047,24 +1047,11 @@ Foam::Istream& Foam::ISstream::readRaw(char* data, std::streamsize count)
     {
         if (data)
         {
-            is_.read(data, count);
+            is_->read(data, count);
         }
         else
         {
-            // Forward seek
-            // - use absolute positioning (see C++ notes about std::ifstream)
-            is_.seekg(is_.tellg() + std::istream::pos_type(count));
-
-            // Not sure if this is needed (as per rewind)
-            // some documentation indicates that ifstream needs
-            // seekg with values from a tellg
-            //
-            // stdStream().rdbuf()->pubseekpos
-            // (
-            //     count,
-            //     std::ios_base::seekdir::cur,
-            //     std::ios_base::in
-            // );
+            is_->ignore(count);
         }
     }
     syncState();
@@ -1083,7 +1070,7 @@ bool Foam::ISstream::beginRawRead()
 
     readBegin("binaryBlock");
     syncState();
-    return is_.good();
+    return is_->good();
 }
 
 
@@ -1091,7 +1078,7 @@ bool Foam::ISstream::endRawRead()
 {
     readEnd("binaryBlock");
     syncState();
-    return is_.good();
+    return is_->good();
 }
 
 
diff --git a/src/OpenFOAM/db/IOstreams/Sstreams/ISstream.H b/src/OpenFOAM/db/IOstreams/Sstreams/ISstream.H
index f1d9a6d615..27859b0086 100644
--- a/src/OpenFOAM/db/IOstreams/Sstreams/ISstream.H
+++ b/src/OpenFOAM/db/IOstreams/Sstreams/ISstream.H
@@ -61,7 +61,7 @@ class ISstream
 
         fileName name_;
 
-        std::istream& is_;
+        std::istream* is_;
 
 
     // Private Member Functions
@@ -135,10 +135,10 @@ public:
     // STL stream
 
         //- Const access to underlying std::istream
-        virtual const std::istream& stdStream() const { return is_; }
+        virtual const std::istream& stdStream() const { return *is_; }
 
         //- Access to underlying std::istream
-        virtual std::istream& stdStream() { return is_; }
+        virtual std::istream& stdStream() { return *is_; }
 
 
     // Stream State
@@ -146,19 +146,19 @@ public:
         //- Return flags of output stream
         virtual ios_base::fmtflags flags() const
         {
-            return is_.flags();
+            return is_->flags();
         }
 
         //- Set stream flags
         virtual ios_base::fmtflags flags(const ios_base::fmtflags f)
         {
-            return is_.flags(f);
+            return is_->flags(f);
         }
 
         //- Set stream state to match that of the std::istream
         void syncState()
         {
-            setState(is_.rdstate());
+            setState(is_->rdstate());
         }
 
 
@@ -180,6 +180,10 @@ public:
             const bool stripComments = true
         );
 
+        //- Associate a different std::istream with the ISstream
+        //  \return the previously attached stream
+        inline std::istream& attach(std::istream& is);
+
 
         // Read Functions
 
diff --git a/src/OpenFOAM/db/IOstreams/Sstreams/ISstreamI.H b/src/OpenFOAM/db/IOstreams/Sstreams/ISstreamI.H
index 84a83df8db..49a41910d9 100644
--- a/src/OpenFOAM/db/IOstreams/Sstreams/ISstreamI.H
+++ b/src/OpenFOAM/db/IOstreams/Sstreams/ISstreamI.H
@@ -37,9 +37,9 @@ inline Foam::ISstream::ISstream
 :
     Istream(streamOpt),
     name_(streamName),
-    is_(is)
+    is_(&is)
 {
-    if (is_.good())
+    if (is_->good())
     {
         setOpened();
         setGood();
@@ -53,9 +53,20 @@ inline Foam::ISstream::ISstream
 
 // * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
 
+inline std::istream& Foam::ISstream::attach(std::istream& is)
+{
+    std::istream* old = is_;
+
+    is_ = &is;
+    IOstream::attach(*is_);
+
+    return *old;
+}
+
+
 inline Foam::ISstream& Foam::ISstream::get(char& c)
 {
-    is_.get(c);
+    is_->get(c);
     syncState();
 
     if (c == '\n' && good())
@@ -69,13 +80,13 @@ inline Foam::ISstream& Foam::ISstream::get(char& c)
 
 inline int Foam::ISstream::peek()
 {
-    return is_.peek();
+    return is_->peek();
 }
 
 
 inline Foam::ISstream& Foam::ISstream::getLine(std::string& str, char delim)
 {
-    std::getline(is_, str, delim);
+    std::getline(*is_, str, delim);
     syncState();
 
     if (delim == '\n')
@@ -89,10 +100,10 @@ inline Foam::ISstream& Foam::ISstream::getLine(std::string& str, char delim)
 
 inline std::streamsize Foam::ISstream::getLine(std::nullptr_t, char delim)
 {
-    is_.ignore(std::numeric_limits<std::streamsize>::max(), delim);
+    is_->ignore(std::numeric_limits<std::streamsize>::max(), delim);
     syncState();
 
-    std::streamsize count = is_.gcount();
+    std::streamsize count = is_->gcount();
 
     if (delim == '\n' && count)
     {
@@ -110,7 +121,7 @@ inline Foam::ISstream& Foam::ISstream::putback(const char c)
         --lineNumber_;
     }
 
-    if (!is_.putback(c))
+    if (!is_->putback(c))
     {
         setBad();
     }
diff --git a/src/OpenFOAM/db/IOstreams/Sstreams/OSstream.C b/src/OpenFOAM/db/IOstreams/Sstreams/OSstream.C
index fd7baf3e9d..cac18ee0cc 100644
--- a/src/OpenFOAM/db/IOstreams/Sstreams/OSstream.C
+++ b/src/OpenFOAM/db/IOstreams/Sstreams/OSstream.C
@@ -88,7 +88,7 @@ bool Foam::OSstream::write(const token& tok)
 
 Foam::Ostream& Foam::OSstream::write(const char c)
 {
-    os_ << c;
+    (*os_) << c;
     if (c == token::NL)
     {
         ++lineNumber_;
@@ -101,7 +101,7 @@ Foam::Ostream& Foam::OSstream::write(const char c)
 Foam::Ostream& Foam::OSstream::write(const char* str)
 {
     lineNumber_ += stringOps::count(str, token::NL);
-    os_ << str;
+    (*os_) << str;
     syncState();
     return *this;
 }
@@ -109,7 +109,7 @@ Foam::Ostream& Foam::OSstream::write(const char* str)
 
 Foam::Ostream& Foam::OSstream::write(const word& str)
 {
-    os_ << str;
+    (*os_) << str;
     syncState();
     return *this;
 }
@@ -125,7 +125,7 @@ Foam::Ostream& Foam::OSstream::writeQuoted
     {
         // Output unquoted, only advance line number on newline
         lineNumber_ += stringOps::count(str, token::NL);
-        os_ << str;
+        (*os_) << str;
 
         syncState();
         return *this;
@@ -133,7 +133,7 @@ Foam::Ostream& Foam::OSstream::writeQuoted
 
 
     // Output with surrounding quotes and backslash escaping
-    os_ << token::DQUOTE;
+    (*os_) << token::DQUOTE;
 
     unsigned backslash = 0;
     for (auto iter = str.cbegin(); iter != str.cend(); ++iter)
@@ -158,16 +158,16 @@ Foam::Ostream& Foam::OSstream::writeQuoted
         // output all pending backslashes
         while (backslash)
         {
-            os_ << '\\';
+            (*os_) << '\\';
             --backslash;
         }
 
-        os_ << c;
+        (*os_) << c;
     }
 
     // silently drop any trailing backslashes
     // they would otherwise appear like an escaped end-quote
-    os_ << token::DQUOTE;
+    (*os_) << token::DQUOTE;
 
     syncState();
     return *this;
@@ -182,7 +182,7 @@ Foam::Ostream& Foam::OSstream::write(const string& str)
 
 Foam::Ostream& Foam::OSstream::write(const int32_t val)
 {
-    os_ << val;
+    (*os_) << val;
     syncState();
     return *this;
 }
@@ -190,7 +190,7 @@ Foam::Ostream& Foam::OSstream::write(const int32_t val)
 
 Foam::Ostream& Foam::OSstream::write(const int64_t val)
 {
-    os_ << val;
+    (*os_) << val;
     syncState();
     return *this;
 }
@@ -198,7 +198,7 @@ Foam::Ostream& Foam::OSstream::write(const int64_t val)
 
 Foam::Ostream& Foam::OSstream::write(const float val)
 {
-    os_ << val;
+    (*os_) << val;
     syncState();
     return *this;
 }
@@ -206,7 +206,7 @@ Foam::Ostream& Foam::OSstream::write(const float val)
 
 Foam::Ostream& Foam::OSstream::write(const double val)
 {
-    os_ << val;
+    (*os_) << val;
     syncState();
     return *this;
 }
@@ -231,17 +231,18 @@ bool Foam::OSstream::beginRawWrite(std::streamsize count)
             << abort(FatalIOError);
     }
 
-    os_ << token::BEGIN_LIST;
+    (*os_) << token::BEGIN_LIST;
     syncState();
-    return os_.good();
+
+    return os_->good();
 }
 
 
 bool Foam::OSstream::endRawWrite()
 {
-    os_ << token::END_LIST;
+    (*os_) << token::END_LIST;
     syncState();
-    return os_.good();
+    return os_->good();
 }
 
 
@@ -254,8 +255,9 @@ Foam::Ostream& Foam::OSstream::writeRaw
     // No check for IOstreamOption::BINARY since this is either done in the
     // beginRawWrite() method, or the caller knows what they are doing.
 
-    os_.write(data, count);
+    os_->write(data, count);
     syncState();
+
     return *this;
 }
 
@@ -264,7 +266,7 @@ void Foam::OSstream::indent()
 {
     for (unsigned short i = 0; i < indentLevel_*indentSize_; ++i)
     {
-        os_ << ' ';
+        (*os_) << ' ';
     }
     syncState();
 }
@@ -272,14 +274,14 @@ void Foam::OSstream::indent()
 
 void Foam::OSstream::flush()
 {
-    os_.flush();
+    os_->flush();
 }
 
 
 void Foam::OSstream::endl()
 {
     write('\n');
-    os_.flush();
+    os_->flush();
 }
 
 
@@ -287,37 +289,37 @@ void Foam::OSstream::endl()
 
 char Foam::OSstream::fill() const
 {
-    return os_.fill();
+    return os_->fill();
 }
 
 
 char Foam::OSstream::fill(const char fillch)
 {
-    return os_.fill(fillch);
+    return os_->fill(fillch);
 }
 
 
 int Foam::OSstream::width() const
 {
-    return os_.width();
+    return os_->width();
 }
 
 
 int Foam::OSstream::width(const int w)
 {
-    return os_.width(w);
+    return os_->width(w);
 }
 
 
 int Foam::OSstream::precision() const
 {
-    return os_.precision();
+    return os_->precision();
 }
 
 
 int Foam::OSstream::precision(const int p)
 {
-    return os_.precision(p);
+    return os_->precision(p);
 }
 
 
diff --git a/src/OpenFOAM/db/IOstreams/Sstreams/OSstream.H b/src/OpenFOAM/db/IOstreams/Sstreams/OSstream.H
index 23318a7646..3a543ba9ac 100644
--- a/src/OpenFOAM/db/IOstreams/Sstreams/OSstream.H
+++ b/src/OpenFOAM/db/IOstreams/Sstreams/OSstream.H
@@ -60,7 +60,7 @@ class OSstream
 
         fileName name_;
 
-        std::ostream& os_;
+        std::ostream* os_;
 
 
 public:
@@ -123,10 +123,10 @@ public:
     // STL stream
 
         //- Const access to underlying std::ostream
-        virtual const std::ostream& stdStream() const { return os_; }
+        virtual const std::ostream& stdStream() const { return *os_; }
 
         //- Access to underlying std::ostream
-        virtual std::ostream& stdStream() { return os_; }
+        virtual std::ostream& stdStream() { return *os_; }
 
 
     // Stream State
@@ -134,21 +134,25 @@ public:
         //- Get stream flags
         virtual ios_base::fmtflags flags() const
         {
-            return os_.flags();
+            return os_->flags();
         }
 
         //- Set stream flags
         virtual ios_base::fmtflags flags(const ios_base::fmtflags f)
         {
-            return os_.flags(f);
+            return os_->flags(f);
         }
 
         //- Set stream state to match that of the std::ostream
         void syncState()
         {
-            setState(os_.rdstate());
+            setState(os_->rdstate());
         }
 
+        //- Associate a different std::ostream with the OSstream
+        //  \return the previously attached stream
+        inline std::ostream& attach(std::ostream& os);
+
 
     // Write Functions
 
diff --git a/src/OpenFOAM/db/IOstreams/Sstreams/OSstreamI.H b/src/OpenFOAM/db/IOstreams/Sstreams/OSstreamI.H
index f559ee5001..35ea994848 100644
--- a/src/OpenFOAM/db/IOstreams/Sstreams/OSstreamI.H
+++ b/src/OpenFOAM/db/IOstreams/Sstreams/OSstreamI.H
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011 OpenFOAM Foundation
-    Copyright (C) 2020-2022 OpenCFD Ltd.
+    Copyright (C) 2020-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -39,13 +39,13 @@ inline Foam::OSstream::OSstream
 :
     Ostream(streamOpt),
     name_(streamName),
-    os_(os)
+    os_(&os)
 {
-    if (os_.good())
+    if (os_->good())
     {
         setOpened();
         setGood();
-        os_.precision(precision_);
+        os_->precision(precision_);
     }
     else
     {
@@ -54,4 +54,18 @@ inline Foam::OSstream::OSstream
 }
 
 
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+inline std::ostream& Foam::OSstream::attach(std::ostream& os)
+{
+    std::ostream* old = os_;
+
+    os_ = &os;
+    IOstream::attach(*os_);
+    // Leave precision untouched
+
+    return *old;
+}
+
+
 // ************************************************************************* //
diff --git a/src/OpenFOAM/db/IOstreams/Sstreams/SstreamsPrint.C b/src/OpenFOAM/db/IOstreams/Sstreams/SstreamsPrint.C
index b1cd14976b..7d9164d67e 100644
--- a/src/OpenFOAM/db/IOstreams/Sstreams/SstreamsPrint.C
+++ b/src/OpenFOAM/db/IOstreams/Sstreams/SstreamsPrint.C
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011 OpenFOAM Foundation
+    Copyright (C) 2020-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -38,7 +39,14 @@ void Foam::ISstream::print(Ostream& os) const
     os  << "ISstream: " << name().c_str() << ' ';
 
     IOstream::print(os);
-    IOstream::print(os, is_.rdstate());
+    if (is_)
+    {
+        IOstream::print(os, is_->rdstate());
+    }
+    else
+    {
+        os  << "std::stream not attached" << endl;
+    }
 }
 
 
@@ -47,7 +55,14 @@ void Foam::OSstream::print(Ostream& os) const
     os  << "OSstream: " << name().c_str() << ' ';
 
     IOstream::print(os);
-    IOstream::print(os, os_.rdstate());
+    if (os_)
+    {
+        IOstream::print(os, os_->rdstate());
+    }
+    else
+    {
+        os  << "std::stream not attached" << endl;
+    }
 }