Ebbie,
I put myself mentally in your position and immediately started having a panic attack. Leaving my home? Living with someone else? Someone who is ill and needs care?
I can't offer advice. I can say that I wouldn't do it.
I am with Spaw on this one. Resettle your sister so she is safe and looked after - and get the rest of the family to participate - and stay with KT in Alaska.
Mary, relaxing on Saba.