I have been working with SCCM 2012 setting up a rolling update schedule. I'd prefer to use the option 'add to an existing software update group'.
The issue I have with this is I'm not sure if this would reset the deadline for any updates already included in the existing software update group. It'd be a pain if my timers were reset just because something new is getting added.
Put another way:
Is the deployment schedule / deadline behavior dictated by the individual updates, or is it done based on the software update group as a whole?