I am interested in this also.
I have so many different machines and some do play well and others just won't play at all.
So it has been my common practice to wait until cycle ends and then push one back.
Also the other day on my Haas VF-5 I was running two programs as subroutines while running my Pallet Pool program and edited one program using Background Edit.
Only to find out the edits I did were not having any effect.
Until I stepped out by hitting reset and re-selecting the program.
Then, the edits were active.
I thought that the main program ( Pallet Pool ) reread the called program each time it needed that program and then my edits should have been read and used.
I hate mysteries.
Mohawk