It's ok if she's not fierce the least she can do is to choose sides actively. Cos seeing her current behaviour this seems to be the best she can do.
Exactly she can just be sure and voice her opinion firmly whatever she thinks to be right or wrong.
Btw when did they changed the arrangement for sleeping ? At first it was decided all men will occupy the hall and the ladies will go in guest room. Now why this distribution on family basis or due to individual's like-dislike.... on a lighter note🤭