Yep - if something were to happen to our daughter, we would fight for custody of the 3 grandkids because the “father” is a druggie who is a RN but starting to self destruct. I’m 67+ and the wife will be 70 in May so it would be a big upset in our “normal” lives, but we would do it anyway - this woman probably never imagined she would have two special needs kids on her hands - tragedy that she couldn’t handle it and wouldn’t give them up to an entity/family that could provide for them.
My only point was it was more than she could handle. Those kids weren’t even able to speak. She probably had to do everything for them, and they were never going to be normal no matter how much she did for them. The rest of her life was going to be entirely consumed by their care, and it doesn’t sound like she was getting much help from the rest of the family. Let grandma do it. Everybody has a breaking point. I would not even attempt what she did. As Dirty Harry said, “A man has got to know his limitations.”