Family Issues Support Group
Family issues is a huge range that go from minor conflict to major misbehaviour and even abuse on the part of individual members of the family occur. Whether you feel you are in a dysfunctional family or you're dealing with a very specific issue, this is the place to talk about it and find others who might be going through the same thing.
Also, I think it's more of an issue between mom and sister. I'd keep my nose out of it since you're the one that caused mom to move...let your mom and sister figure things out in their relationship. It really not about you, but sister's feelings towards mom's decision.
On a different note, please realize how lucky you are to have family to support you through your pregnancy and birth. I too had a horrible pregnancy and c-section. My son was born at 35 weeks 5 days; he spent to weeks in NICU due to a lung infection and not feeding properly. My family never visited (they live between 15-20 hours away by car). My husband's parents visited once (very briefly) and they live in the same town we were hospitalized in. You are truly blessed.