I agree with Karen. We all love our families and we hate to see anyone in a bind, but I sense a trend here. Helping out here and there is ok, but sounds like you are bailing Sis out when she needs it. She might need a dose of "tough love". You will be doing her a favor to let her stand on her own two feet. I would talk with her about what you are willing to do in this situation - set some boundaries - and then do it. It will never feel comfortable - good luck to you.