It’s not even my MIL!

My mother in law babysits my daughter during the day she is also the care taker for my chronically ill sister in law. My mother in law is very abiding. If I talk to her and tell her what I want and expect she makes every effort to abide and I’m grateful what grinds my gears is when I’m two sister in laws act like they need to question every. Single. Thing. I say and do that chaps my ass. They have never had a boyfriend let alone have parenting skills. I say my 13 month old doesn’t need 4 6oz bottles a day she doesn’t. She is eating just fine drinks lots of other fluid at this point her bottles are more for comfort and supplementing. At 13 months my daughter understand some Spanish, English and sign language. Her pediatrician is super happy with her growth and development she is excelling. I just want to scream at them and tell them to have/adopt their own kids! I’m really trying to be nice and respectful but I’m getting irritated with it. Am I over reacting?