I'm certainly not offering any legal advice, but doesn't it make you wonder if these guys only care about money? It's my understanding that you can only clain the mortgage interest deduction for a place you reside. So I'm not sure what he's asking for unless he is trying to get himself audited.
My Ex - now for 5 years, is STILL attempting to gain something from me to enrich himself. I claim one of our sons and he claims the other. He wants me to give up the other so he can claim both. What he REALLY wants is for me to give up my rights to his retirement, which I will not do. The tax consequences are huge. Head of household has a much lower tax burden than single. If I were you, I'd give him the oldest child (mine are twins so it does not matter).
Your suggestion sounds fair to me. He's pissy because he cares only about himself. Stay strong and keep what you can for yourself.
