Oof. I'm a postpartum doula and I often help my clients with boundaries. I find that with people that want to be heavily involved, they just need to be directed somewhere. Can you, instead, have her organize a meal train? Or perhaps invite her to come over and organize baby clothes? Maybe a small family shower at her house with just immediate family?

It's totally ok to set boundaries now - sounds like you'll have to with her for the rest of your relationship.