You mean like a squad? Yeah, it's possible. Requires triggering. I don't remember exactly how to do it, but I do remember seeing a tutorial on here about it. Try looking in the Tutorials section. Search for like, "Sqaud" or "Leader" or something. xD
To clearify, basically what you want is:
You order one unit to do something, and all the other units in it's "Squad" are ordered to do the same thing? Like, if you order them to stop all the others will do. If you order them to attack, all the others will. If you order them to do a spell, the rest of them will do it too.