((((hugs)))) I'm so sorry. Initially, the supervisors for AXH's visitation with our son were AXH's father and sister. DS has since told me that his Grandpa would go to walk the dog and not come back. One time, XSIL took DS and refused to bring him back.
If AXH ever comes back to try to win back visitation with DS, I will not agree to his sister or a new GF being the supervisors. (I feel so naive saying this, but) I realized after-the-fact, after finding out what DS's time with AXH and family or GF was like, that: 1. XSIL was part of the same family dynamics that created abusive AXH. (I need to force myself to examine why I still think XFIL was so sweet, and couldn't possibly have had a hand in it.) and 2. Any new GF is just going to be part of the abuse cycle, unless and until AXH changes. Or she won't stick with him for long.
I'm so sorry for what your daughters have gone through. I'm glad, though, that she felt safe enough to bring it up. (((((hugs)))))