How do I stop my stepdad [60sM] from holding my baby

I’m estranged from my stepdad [60sM] who is unfortunately still married to my mom [50sF]. My stepbrother [30sM] is also estranged.

Without going into a ton of detail, he’s extremely narcissistic and is deeply unpleasant to talk to. I believe he financially and emotionally abuses my mother. He encourages her to make horrible financial decisions that put them both in precarious situations, including emptying out their retirement accounts without considering the tax consequences (and obviously long-term consequences) that put them in serious financial straits for a few years. He prevented my mom from visiting me several times and for a while only let me see her if he was there.

He also borderline abused me as a teenager and has a history of poor boundaries with his students and people around him. He’s been fired/asked to quit from a least two teaching jobs because of “false accusations” and has recently been the subject of a CPS investigation after making an inappropriate comment to one of his students. He gets cleared every time or nothing ever comes of the accusations, and after knowing him for several years I think he’s extremely good at avoiding crossing the line between behavior that would 100% get him caught/permanently fired.

He’s had very poor boundaries with me in the past (e.g. asking me to proofread a book he wrote that contained dozens of sex scenes, gifting me erotica as an 8th grader, etc.) and continues to have poor boundaries with strangers (e.g. he randomly said something like “my 20s were all about dancing and sex” in his first conversation with my BIL. wth). As an adult now, I could absolutely never imagine doing something like that with a child, stepchild or any teenager in my care. Especially if I had been “haunted by false accusations”.

Unfortunately my mom doesn’t care or doesn’t feel like she can do anything about it, at least partially due to her dependence on him. She’s also a teacher, and when I’ve told her about things my stepdad has done and ask “if one of your students told you this, wouldn’t you say this is abuse and grounds for mandatory reporting?” and she’ll say “yes…” but continues to dismiss his behavior. Whatever, I’m over it.

I’m currently pregnant with my first child and for obvious reasons the thought of my stepdad interacting with my child make my skin crawl. I don’t want him holding her, touching her, giving her gifts, or anything like that. To be honest I think it’s unlikely he would actually hurt her, but I don’t know what he’s capable of and there’s no way I’m exposing my daughter to him.

I’m forced to see my stepdad at an upcoming family reunion where I’ll hopefully have a ~6 month old daughter with me. I want my grandparents and mom to hold my daughter, but not my stepdad. If I explicitly set a boundary like “Stepdad is not allowed to hold daughter” I’ll get painted as manipulative, dramatic, etc. by my mom/stepdad and I’d like to avoid that if possible.

Stepdad is extremely manipulative and will use this as further grounds to isolate my mother from me. I might have to do this regardless but I’m wondering if there are more subtle ways to stop this from happening for my mom’s sake.

How should I go about making sure my grandparents and mom don’t pass the baby off to my stepdad or leave her alone with him? Do I prevent them from holding her altogether?

tl;dr: I don’t want my creepy stepdad interacting with my future infant daughter without giving him fodder to alienate my family from me. How do I prevent my grandparents/mom from passing my daughter off to him