I think I may have found the answer to my own question. I'm posting for anyone else who may find the information helpful.
In my case, either of the following would work. 1. Father has not seen or supported his children for 2 yrs or more and 2. father has voluntarily terminated parental...
He had abandoned her. He'd pop in and claim to be her dad but then he wouldn't contact her again for a long time. That's already done though. He has no rights to his youngest. Who signs off on one child and not the others? You can't say you want nothing to do with your youngest child but...