Condolences to your family and I guess just a kudos to you for how you have handled this and cared for your Mom and sister. I worked in the disabilities field for a long time and family dynamics can be interesting. You sound like an amazingly supportive person.
The last few years with my Mom were tough with her dementia. If there is one blessing that came from it, it would be my sister and I spending more time together. She is a trooper and a natural care giver. When she moved further away, I took on more responsibility. I more than owed both of them that much. I did meet many people in her facilities that had no one. It was very sad. I used to take our older dog there and just hang out. Everyone lit up when Gracie was there. Especially my Mom.