What I am trying to say is that it seems like I have to compete to be able to care for my son. She needs to let me mother my baby, as she had her chance to mother all three of her children.
You girls are not alone with this feeling! It's terrible!
This ^^ and I'm still trying to find a tactful, polite way around it. My in-laws gang up on me and never allow me to be with my baby. They just pass her around from one to another and rush her out of the room when she gets fussy so they can try to hide it. They just refuse to give her up and I can't understand why, especially now that she can communicate what she wants. She's in the phase now where she
reaches for me and they still try to purposely distract her away from me! Now I boldly follow them around and snatch her back up, which has created some lovely tension.
When LO was three months old, we went to a birthday party of a mutual acquaintance and I was pushed on the sidelines while they did what they wanted with her.
My first Christmas with my first baby, they completely took over. I didn't spend one moment with my baby during Christmas, she was in their laps just being passed around while looking dazed and finally, crying hysterically. (Then, just giving up and going into overtired mode.)
By the time we got home, my LO was up all night screaming in her sleep from overstimulation!
i finally had enough and have learned to be a lot more assertive (ie, getting right up in their face when LO is being fussy and saying, "Ok, Mommy is taking you now.")
But, really, it doesn't matter if it's the in-laws or my own parents. I've become invisible.

They basically just come up and snatch my LO out of my arms. I know they're well-meaning and love her so much, but it's irritating.
I take a deep breath and say, this too shall pass. LO has many people that love her and battle for her affection but it's really overwhelming sometimes. Especially when they view you suspiciously because you don't do things the way they feel you should.
But being a Mommy has taught me one thing; how to be a bitch and not apologize for it. Not to care about anyone's opinion because (as I've discovered)
everyone has a opinion once you have a child.
I just try to stay busy now when other people have her and get what I need done. The separation anxiety eases with time. And, no matter what the opinion is, at the end of the day we are still their Mommies, and ultimately we have final say on everything concerning our babies.