This can be one of the most frustrating things for a mom...and often, mom is creating her own frustration simply by being there.
Here's the trick:
Hand baby to caregiver.
LEAVE. Out of the room, out of the house.
Mom giving baby a bottle is frequently an exercise in futility, and here's an analogy to explain why:
Your breasts = grandma's fresh-baked cookies, right out of the oven.
A bottle = Stale, store bought cookies.
YOU giving a bottle = grandma giving you the stale storebought cookies while she waves a plate of her hot, fresh cookies under your nose, all the while not allowing you to touch the fresh cookies. All you can do is be tortured by the delicious smell.
Baby's nose is keen. Don't torture him with the delicious smell of your fresh milk while trying to offer him the other stuff.