You have two young children with one on the way and now you're caught up in your sisters drama? You are a good sister and a good friend! You should put you, your own family and your grandmother above all else. You sister has to want to change and want help until then there is not any thing you can do for her. I know it is easier said then done (boy do I ever know it!!!) but sometimes you have to walk away. Everyone can't be in your life. ((hugs))