#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?m-s)(?:^(?=.*\bbar\b)|(?!^)\G).*?\K[ ]{2}"
Local $sString = "foo: here is some sample text" & @CRLF & _
"bar: here is some sample text" & @CRLF & _
"" & @CRLF & _
"The closest that I've gotten has been using this:" & @CRLF & _
""
Local $sSubst = "\\t"
Local $sResult = StringRegExpReplace($sString, $sRegex, $sSubst)
MsgBox($MB_SYSTEMMODAL, "Result", $sResult)
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for AutoIt, please visit: https://www.autoitscript.com/autoit3/docs/functions/StringRegExp.htm