Interesting about the boy child. -They say, children pick up these things easier then adults because they havent been "taught" not to see them yet. Animals are also meant to be sensitive.
If I can throw in my 2cents- I wouldnt be keen on somebody bringing along something/body to my birthing if they didnt know who it was- interesting about your MIL though, and how the events transpired, made me smile.

Im not sure how to take- some spirits need life energy to move around. That would certainly make me wary. Its something that needs somebody far more experienced then me to comment on that.

She sounds like an interesting friend to have