What is PMDD ??

I would guess that the best thing you can do - since you are only 16 - is continue being a friend to your friend and her little sister. It is not likely that an adult woman - even one who is struggling with parenting issues - will take the advise of a 16 year old child. Even though it sounds like you are able to see patterns and areas of opportunity that the other mom cannot.

Your friend is lucky to have someone in her life such as yourself - it can't be easy for her living in a chaotic household. I'm sure you bring some peace and comfort to her.

You sound like a wonderful friend.