Sounds like life to me, nothing really to worry about. If you break it down it really is their deal not yours.
Your Daughter seems to not be able to let go of stuff, which she needs to work on.
The thing with your sister is just a lack of communication, and you son needs to grow up.
Ok that’s that, now it’s over!
Think more about you and things will be fine. These are all adults who need to do for themselves.