how to handle my mil

My husband and I both have two sets on inlaws. Being a stepmom I get being left out and feeling like you don't have a say.
His stepmom can be difficult to deal with. She hasn't had an easy time of things, I try keeping that in mind. I'm out of town for a conference and they are visiting my my husband and stepson - we are expecting and she has been sending us stuff. I want to make a registry and let everyone feel like they are involved; I feel like a registry and a shower are part of the excitement that comes with a new baby. So while I was annoyed, I said thank you to her for being so generous and I thought we were fine. Anyway, this weekend she cornered my husband, which she does, and I don't even know - made me sound like I am leaving her out or refusing to be her friend. My husband said I could try harder to be nicer - I was pretty furious. We FaceTime with them every other weekend when we have my stepson, we visit them every thanksgiving (I always bring something, coffee cake or pie), we see them right after Christmas, I always make sure she has a Mother's Day gift and card (which I coordinate and plan and ship out), I've sent them ultrasound pictures after my appointments - I guess I'm missing what else I should be doing. I don't feel like I need to be best friends with her. Her generousity is self serving - she likes being praised for what a generous person she is and I say thank you, this is so thoughtful. Am I missing something? 😕