ok how does this work then...i just found this:
There's some weird interactions with that, though. Say you cast Undead Psychosis at a Guild crew, and one of the extra 'targets' you pick is within 3" of Sonnia (but the main one isn't)... in theory she could use Advanced Counterspell to cancel a spell on the target, but that has to be done before the starting casting total is generated (which is impossible, since the 'target' isn't a target at that point). It's not too hard to resolve that (she just can't do it, boo hoo) but I'm sure there are other weird issues with making the additional defenders 'targets'.