adoption and future

My fiance signed away his rights and adoption papers for a daughter he never knew to be adopted by a guy who has been with the mother and daughter since day 1, I will never understand why the mother had to insist he was still the father, it could of been more simple if she would of omitted him from their lives. Anyways, my question is, what if this adoption doesnt go thru for some reason, say the other man leaves and the adoption is incomplete, will this woman be able to go after my fiance for support again? We have papers signed in court to stop support due to the adoption. Is there anyway for us to find out if the adoption does go thru. We want to protect ourselves from any future harrassments from this woman in the future, and we would like to know all the what ifs. Any answers is greatly appreaciated.
Thanks,

If the adoption is finalized, that ends his current child support obligation. It does not erase any arrearage owed, however.

If the adoption does not go through, he could still be on the hook for support.