Regexp:
Local $sIn = _
"FIN,MRN,LastNameA,FirstName,DateOfService,Mercy Dept Name,ServiceCode" & @CRLF & _
"FIN,MRN,LastNameB,FirstName,DateOfService,Mercy Dept Name,ServiceCode" & @CRLF & _
"FIN,MRN,LastNameC,FirstName,DateOfService,Mercy Dept Name,ServiceCode" & @CRLF & _
"FIN,MRN,LastNameD,FirstName,DateOfService,Mercy Dept Name,ServiceCode" & @CRLF & _
"FIN,MRN,LastNameE,FirstName,DateOfService,Mercy Dept Name,ServiceCode" & @CRLF
Local $sOut = StringRegExpReplace($sIn, "(?m)([^,]*,[^,]*,[^,]*),(.*)", "$1 $2")
ConsoleWrite($sOut)