How Can a Fiancé Adopt a Child Without the Other Parent's Consent

My question involves adoption law for the State of: Pennsylvania

I have a 22 month old with one guy and he has not really been in her life since she's been born. He recently just started paying me money every week for her and sees her maybe 0-3 times a week (thats all on his own dession not mine). I have been with a new guy now for a year and were engaged and I have a 4 month old with him and he wants to adopt my first daughter without the other guys permisson. My first daughter has my last name and not her fathers (his name is on the birth certifi, So would my fiance be able to adopt her with out his pemisson since she does not have her biological fathers last name? Or would we have to be married first in order for him to adopt her. I'm just looking out for her sake because her biological father got his gf pregnant so he wont be around much even thou he says he will be which I dont believe cause he has been saying that her whole life.

He's the legal father - her last name is completely irrelevant. Given that he apparently wants to be part of his child's life, even if you get married a stepparent adoption will not happen.