help! my MIL is driving me crazy!

Karen
My little one is 4 weeks old, super tiny as she was born a whole month early. Now I'm not usually a fanatic when it comes to baby but everytime my MIL holds her, she does her damnedest to wake her up if she's sleeping, or she likes to hold her upside down or she holds her up in the air and says "weeeeeee" even if baby is crying and obviously not enjoying herself. She doesn't use appropriate neck support in my opinion either. She's always moving her around in strange jerky motions and I'm afraid to say anything because she's super sensitive and sweet and I don't want to hurt her feelings 😐