talk to PZ about being there for the first visiting hours - if she can help you to stand up to the Ob's during your birth, i'm sure she can help you stand up to family!
I get the feeling it's going to be hard to get rid of her

Haha, after all this worry I bet I only have two or three visitors outside of my parents/brothers at the most! I do tend to overestimate how much people actually care about me (I really want to word that a different way, because it's not quite what I mean, but meh.)