My daughter's situation is causing me a lot of angst
It is easy to overthink things and try to "care" for her...she is your daughter. However, she is an adult, she has children and it is her prime responsibility as to how to bring up her children. In saying that, while she is under your roof, it is ok for you to lay down some basic groundrules of behaviour that you would expect of anyone else, but be careful they are not being colored with your wish to control.
We have an overseas student staying with us at the moment. It frustrates me somewhat to see her behave in such a selfish way. However, I have determined to back off, and allow my wife to run the show here, with me spending time talking to her about my concerns rather than causing any angst with the student. Have you got someone you can talk to about this? Or can you talk sensibly and rationally with your daughter away from the hearing of the children?