Spacecase,

Let me tell you from experience, if holding on to the relationship with your sister is worth everything you have to do in order to achieve it, then DO IT. Even if that means leaving your dysfunctional parents behind to fend for themselves. You are NOT responsible for your parents. But if your sister means this much to you, there are two things you need to do:

First, talk to her. Tell her how much she means to you. Tell her that she is very important in your life and you would very much like to live near her. Get her reaction. Make sure she is OK with that. Also make sure that she understands that you do not want her to feel any guilt or responsibility with regard to her moving. It's just that you want to live close to her even if that means moving away from your parents.

Second, if all of the above seems ok, then make some solid plans that will enable you to accomplish what you want. She may be willing to help you. But she may not. She may not be able to help you in the beginning and it may take a while before she can. Circumstances will dictate that.

It's always a possibility that the subject may come up regarding "who will take care of mom and dad". The truth is, it is not up to either one of you to do that. And it is not a healthy environment, either. You may find some resistance from her on that. But, let's not jump ahead too much. These things can be dealt with as they come.

I hope some of this has been helpful. I have lost my relationship with my only sister over a disagreement we had several months ago and it still hurts. I hope the same does not happen to you.

Best of luck.