Last Name

How do you feel about giving little one dads last name. I have a son and he has his dad last name and I regret it because his dad doesn’t help take care of him. But I always thought, since I know he’s the dad, he was around during my pregnancy so I thought it was the right thing to do to give him his dad last name. This time around, my daughters dad has repeatedly reminded me that he told me not to move forward with my pregnancy and I’ve pretty much went through this pregnancy by myself. He’ll check on us like once every week or two week & if I go grocery shopping he offers to bring them in my house. But that’s about it. He been to 2 of my 10 appts. But he says he will be there to help when she’s born. But at this point i don’t really know. but I’m also big on being fair

& I don’t want seem bitter.