How much effort should I put into maintaining a relationship between my dad and my son?

I don’t have a relationship with my mom anymore after years of trying to make it work with her. My step-dad met my mom when I was basically 1 month old and they’ve been together since. He ended up working for her family’s business and I’ve always kind of thought he was trapped in the marriage with her, but no one knows for sure. He certainly knew about the abuse she inflicted onto me and he was always the one to try and smooth things over after her episodes.

So I haven’t spoken to my mom in about 6 months and recently realized I hadn’t spoken to my stepdad much either. My biological dad is extremely flaky and although he lives next door I see him maybe once every few months and only if I basically badger him into seeing my son. He said he was going to come over the morning of my son’s birthday and then never did, never said anything and just didn’t show up, and he also said he was going to get my son a specific gift that I told him I was going to get, so my son never got it. For the last few weeks I decided to just drop the rope and not contact him to see how long it would be until he reaches out to us. So far silence.

So I guess in the absence of my biological dad, I was clinging onto some semblance of a father relationship and told my stepdad we miss him and asked him if he’d like to come over to spend time with my son. He agreed (I was surprised bc I didn’t invite my mom) and asked if my sister and her baby can come too, I said yes and they all came over for a few hours. The visit went well and they didn’t mention my mom. Btw, my son’s birthday was a few days earlier and my step-dad completely ignored his bday, didn’t say happy birthday via text, call, or in person. I don’t expect a lot but at minimum telling him ‘happy birthday’ when he was here would have been meaningful.

That was about a week ago and I haven’t heard anything from my stepdad. I was kind of thinking he would text me after the visit and thank me for having him over or initiate another plan. But since there’s just silence, I feel rejected again.

Should I just drop the rope with both of them? I feel like it shouldn’t take so much effort to maintain a relationship with my 2 dads. My husband’s family is very happy to visit and very supportive to us. So it’s a huge contrast.

I don’t think I’m mean or unwelcoming when they visit, my son is very well behaved and my house is clean. My husband is very social with them bc they all have similar hobbies. I’m just not sure what I should do here.