File with no TPR?

Weird question here. We are in a foster situation. TPRs are final on the birthmother and putative father. The putative father's name was not on the BC and DSS never did a DNA. Everybody just accepted him because he and mother lived together several years before conception and through conception, birth, and a few years after. Come to find out mother was still legally married to someone else until a few months after the birth. All along, the cw kept telling me it was no big deal, DSS as far as I know made no effort to get his name, marriage/divorce records, etc. Well, talking to our adoption attorney, she said that wasn't OK. So, we researched, found him, gave the name and info to DSS. For some reason (maybe $?), they did not just serve him, wait for him to not respond, then TPR; instead, they have asked him to sign "an affidavit" or some kind of consent, the same as a first father might do for a step parent adoption. He told them he would, but it's been over a month and he hasn't. He is a lawyer himself and it is hard to imagine him voluntarily acknowledging any kind of paternity that might put him at risk for back child support? We can't petition for TPR on him because we don't have legal custody--and don't want it short of adoption, she needs to stay in the fost-adopt system with her Title IV-E and Medicaid, we can't take care of her physical and mental health needs without it. So...we really want to move forward with this adoption. DSS and the court in the state where that would happen don't seem to care two hoots about a legal father in another state. What could be the ramifications if we go ahead and file and finalize without TPR on him?