Step parenting & favoritism?

I have a school-age child and my husband has no bio kids. His family didn’t like me because I was a single mom broke & in college when we married. (Now I’ve graduated and make significantly more than he does.) They weren’t kind to my child, so I ceased all contact with them years ago and my husband sees them on his own. It’s not ideal but we’re close with my family who’s supportive so I don’t think about it much. However, he and I are discussing having a baby together. My immediate concerns are that his family will want to be involved with this child because they will feel some kind of ownership over it due to it being a blood relation, while they certainly didn’t treat my existing sweetie like a grandchild. I don’t want to bring them back into my life. I am also so worried that my husband will prefer the baby over my child. My child’s father has never had custody due to him making terrible choices and he only bothers to see him a few times a year (he has supervised visits & lives right down the road). My son doesn’t have a bond with his bio dad but does with his stepdad. I would never want to make any choice that would make my child feel bad as he already has hurt from his bio dad.

Does anyone have experience with this?