#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?ms)#{3}(?P<town>.*?)(@{3}\n.*?)(&{3}(?P<person>.*?)(\^{3}\n))+?"
Local $sString = "STARTOFTEXT" & @CRLF & _
"&&&Aragorn^^^" & @CRLF & _
"###The Shire@@@" & @CRLF & _
"&&&Frodo^^^" & @CRLF & _
"&&&Bilbo^^^" & @CRLF & _
"&&&Pippin^^^" & @CRLF & _
"###Gondor@@@" & @CRLF & _
"&&&Faramir^^^" & @CRLF & _
"&&&Boramir^^^" & @CRLF & _
"ENDOFTEXT"
Local $sSubst = "\g<person> is from \g<town>\n"
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