Here is a simple example.

This script will start and call a copy of itself (with a $iTimeToSleep parameter)

The main (parent) script will exit immediately, but the child script will continue to run in the background.

Code:
Break ON

If IsDeclared($iTimeToSleep)
	"Child script called"+@CRLF
	"Sleeping "+$iTimeToSleep+" seconds"+@CRLF
	Sleep Int($iTimeToSleep)
	"Child done sleeping, will now exit..."+@CRLF
	Exit 0
EndIf

"Parent started, will call child..."+@CRLF
RUN "kix32 "+@SCRIPTNAME+" $$iTimeToSleep=3"
"Parent called chiled - will now exit"+@CRLF
Exit 0


In the real world of course your child script would probably be a completely different script.