Future step mom

I say future because we're not married yet but my bf has kids and I'm 9 months pregnant I was wondering if it's weird for me to reach out to the other moms to try and get to know them and see if I can pick up the kids etc.. We just found out about one baby and he told me he didn't know that his little brother had set up a time to go meet the baby without him which I found out and never believed in the first place that it wasn't true he did know and he just didn't go.. He. Also didn't go see the baby the first time he was supposed to.. I wrote the new mom and asked her if she has set up any other times with him and maybe if her and I can get to know each other because I know with the first bm it's dead she's never going to like me and that's fine I wish things would be different but oh well I have learned to live with that and that her daughter and mine probably won't meet for a long time since we haven't even seen her daughter since May smh .. But I want to try with the new mom at least.. Is that weird? Am I crossing a boundary.. Should I mind my business? I feel like if he's going to be a father to my daughter even though I know it's different he was there for my entire pregnancy we're in a relationship etc that he should be there for his others just like mine even if he didn't know about the new baby and that him and his first bm never actually had any kind of relationship just sex and he wasn't there at all for her pregnancy or anything but I want him to be now it's not fair to the other moms or his other kids smh