My daughter has problems that are different than others on here so maybe no one relates
I think your daughter's (and your own) issues are very like the majority of us here with our adult children. Most of us are older. And most of us can't or won't any longer take on our children's problems, because they behave unacceptably, have worn out their welcome, treat us badly, we're sick and tired, because it's time for them to deal with their own lives, or all of the above. None of us feel good about this. We would want to see our children prospering, safe, happy and normal. Nobody comes to this site, when all those boxes are checked.
What in the world could you do to save your daughter and her children, even if you were young and healthy? People live as they are able, and as they choose. Your daughter seems to want people to support her in every way, with no strings attached. She is not responsible for good conduct, being respectful, or reciprocity of any kind. The people who take her in are in one way or another abused.
You say, nobody wants their possessions destroyed. You're a person, too. And you don't want your things destroyed, your sanity eroded, your peace of mind and tranquility and safety taken from you, and why should you? Your daughter may feel entitled to take all those things away, but you are not obligated to give them to her. Your daughter is the one who is neglecting her children and their welfare. If it gets bad enough authorities will step in to protect them. There is no reason for guilt here.
PS As ksm explained, the site went through some real difficulties and was shut down. There are just a few of us left who take responsibility to respond. We have jobs and grandchildren and health issues. We do what we can. We would love it if you help us respond to posts. Welcome to you.