I would file the paper return claiming the child and attach a statement (not that anyone at IRS will read it) that "Receipt of Form 8332 is Pending."  It has been a few years since I saw one of these, but the first time around when the same individual appeared on two returns, IRS just sent a letter to both of them saying "don't do that again."  Evidence of disallowance by IRS may be helpful or necessary in any state court proceeding. 

Good questions -- what's the date of the decree, and how old is the child?