Baby fell from couch onto floor. 2nd time and baby is only 3 weeks old. Mom is exhausted/overprotective. Advice?

Before anyone assumes. The baby isn’t mine. I’m in my mid 20’s but the baby is my mother’s. I was an only child until recently.My mom raised me when she was a teen but had help from my grandma. Now she has gotten remarried and this is her first baby with her husband. Only this time it’s mostly her instead of my grandma. Since by now my grandma is too old to help and lives in another country. So it’s like she’s a new mom all over again.This is the 2nd time my mom has fallen asleep and dropped my sister. She screamed and was crying when I went over to grab the baby from her.She was freaking out and screaming that I had to yell at her to leave because she was making the baby cry more. I sent her away and checked over the baby. Besides a red mark I assume is from rubbing the carpet when she fell, rather than impact by her nose. She is perfectly fine.I checked her arms, legs, head, and eyes (just like when we went to urgent care for her first fall) while my mom panicked and cried from the guilt nearby.I told her the baby was probably fine but now she feels so bad she’s been alone in her room crying and feeling guilty. I’ve been watching my sister since.Personally I feel my mom is so protective it’s becoming dangerous for the baby.She always wants to hold her and hardly lets the baby’s father even help out. Therefore she’s the one doing everything for my sister 24/7 and it’s beginning to wear her out. She’s absolutely exhausted. My mom is also very stubborn and often wants things done her way which fuels her desire to do everything herself.Her husband however is pretty bad at handling the baby too. The other night my sister was screaming and he couldn’t calm her down because he still doesn’t know how to hold or handle her. He’ll hold her and won’t support her head. I ended up getting so irritated with him I grabbed my sister and got her to fall asleep. Then I taught him how to properly hold a baby. It annoys me that’s I had to teach him how to hold her and comfort her when I haven’t even had any kids of my own. It’s not even my kid but I already know more than he does.But my mom doesn’t even like letting the baby sleep in her crib, she has to have her nearby or holding her. The baby has an ankle heartbeat monitor and my mom refuses to let her sleep without it on. I mean I was born in the 90s and I obviously survived without a WiFi monitor. But to each their own.How do I help my mom realize that being overbearing is harming my sister? How do I help her with her guilt? Will my sister be mentally affected by any of this?Ultimately I’m worried about my sister and her wellbeing. via /r/Parenting https://ift.tt/2SxgvEN