Modifying %Stream contents

I have a %Stream that I want to insert some text into the middle of.  I create a new stream called pNewContentStream from the original stream, then I do a MoveTo in pNewContentStream to get to the byte position I want to insert into but when I do my Write, my pNewContentStream gets obliterated with only the text that I wrote, the original content goes away and all I'm left with is my Write text.

Method AddContentTypeCode4(pContentStream As %Stream.GlobalCharacter, Output pNewContentStream As %Stream.GlobalCharacter) As %Status
{
Set tStatus = $$$OK
try {
Set tTemp = pContentStream.Read()
$$$HSTRACE("AddContentTypeCode4[1]","tTemp",tTemp)
Set pNewContentStream=##class(%GlobalCharacterStream).%New()
$$$HSTRACE("New Stream")
Set tStatus = pNewContentStream.CopyFrom(pContentStream)
$$$HSTRACE("AddContentTypeCode4[2]","tStatus",tStatus)
Do pNewContentStream.Rewind()
$$$HSTRACE("AddContentTypeCode4[3]","pContentStream,pNewContentStream",pContentStream,pNewContentStream)
Set tLocatorString = "<ns2:Description>"
Set tInsertPoint = pContentStream.FindAt(1,tLocatorString,.tStr,0)
Set tInsertPoint = tInsertPoint+$LENGTH(tLocatorString)
$$$HSTRACE("AddContentTypeCode4[4]","tInsertPoint,pNewContentStream",tInsertPoint,pNewContentStream)
Set tStatus = pNewContentStream.Rewind()
Set tStatus = pNewContentStream.MoveTo(tInsertPoint)
$$$HSTRACE("AddContentTypeCode4[5]","tStatus",tStatus)
Set tStatus = pNewContentStream.Write(..ContentTypeCodeInsertable)
$$$HSTRACE("AddContentTypeCode4[6]","tStatus,pContentStream,pNewContentStream",tStatus,pContentStream,pNewContentStream)
Do pContentStream.MoveTo(tInsertPoint)
Set tRemain = pContentStream.Read()
Do pNewContentStream.Write(tRemain)
    
     $$$HSTRACE("AddContentTypeCode4[n]","pContentStream,pNewContentStream",pContentStream,pNewContentStream)
     /// Set pNewContentStream.ContentType = tContentTypeCode 
} catch ex {
Set tStatus = ex.AsStatus()
}

The trace labeled "AddContentTypeCode4[6]" shows tStatus = 1, pContentStream is intact and is as expected, pNewContentStream contains whatever was in  ..ContentTypeCodeInsertable

What I was hoping to happen was at least having the beginning of pContentStream, then have the contents of ..ContentTypeCodeInsertable but instead I only get the contents of ..ContentTYpeCodeInsertable.  Any suggestions?  Thanks!

Marlin