2 - What about it? Can you control what your W does? Can you control what your sister does? No. So why look like a control freak in trying to do so? Hell, use the situation to your advantage. When your sis asks you how you're doing, let her know you're doing GREAT. When she asks about the situation, simply say it's not worth discussing and then say you have to go do something, MUCH LIKE YOU WOULD TO YOUR W. This will in turn get back to your W via your sis who will also be questioning what you're up to, why you're so upbeat and busy.
I agree, you DB your sister. They all are watching you. No drama on your part because you can handle it by yourself.
Cheers
M22,H45,W45 S21/18D12 Retain faith that you will prevail in the end, regardless of the difficulties and at the same time confront the most brutal facts of your current reality, whatever they might be.