Parent Taking Money From Disabled Child

Location: Massachusetts.

One of my adult siblings has developmental disabilities and lives in a group home. She receives monthly SSI payments, of which 75% gets paid to the agency for rent. She has been in the same house for more than 20 years and is very well cared for.

My mother is the legal guardian of my sister, which means she has access to her bank accounts. To say my mom is bad with money is an understatement, and over the years she has “borrowed” from my sister’s account on occasion. Over the past year, it turns out that she has not only been taking money, but taking so much that my sister’s rent has not been paid. I don’t have an exact number of what is owed but she has implied it’s in the $5,000 range. When confronted about the legality and morality of what she’s doing, mom’s response is that she has no choice because other family members are not helping her enough financially.

I would like to have her access to my sister’s accounts blocked. My questions are:

1. Is it possible for her to remain the guardian for things like medical care while having someone else appointed as financial guardian?

2. If she is not willing to voluntarily transfer guardianship to someone else, what would my legal steps be?

3. If I/my family pursues legal action to change guardianship and we have to give our reasoning, would she then automatically be charged with a crime?

4. When looking for an attorney, what area of practice would this fall under?

Thanks!