Every time my DD's friend has a row with her mother, she is grounded, meaning she can't go out with my DD, often at short notice, leaving my DD festering at home feeling upset. I would tell DD to tell this friend to get lost but DD is a fairly quiet girl with few other friends and is also easygoing so puts up with a lot as she doesn't want to have even fewer friends to do stuff with.
Should I intervene in this situation and say something to the friend's mother or just leave it to my DD to sort out? I am fairly friendly with the friend's mother but I am fed up with my DD being a victim of the rows between the mother and her DD, which are nothing to do with my DD?