Have one adult child living away from home but currently part-dependent on us for financial support as the school she attends does not give access to student loans. She has medical issues, is part-disabled and has some MH problems, mainly a tendency to severe anxiety. Basically, she knows she can ring any time of night and day and I will listen but not come running. Will be more likely to listen than try to problem solve, but if I do make suggestions she knows I will not be offended if she rejects them. She has made it clear that she needs to be able to rant about people at times and trust me not to take against them forever, but she also knows that I have the right to say "ok, I don't think I can take more ranting just now". I also know her well enough to know the kind of topic that will help to lead her thinking into more positive territory. When she lived at home & was working, she contributed part of her salary & shopped & cooked one meal/week.
She would also listen to me if I needed an understanding ear, provided she is well enough mentally. And if one of us needed help, she would try to be there for us.
Also have a 19yo living at home, having just left college. He is currently on holiday with us, but is looking for work. Will be expected to make a financial contribution & provide one family meal/week. Basically gets treated as an adult: is expected to let us know when he is not going to be in for supper & when he won't be coming home at night, but otherwise allowed to come & go as he pleases, as long as he doesn't disturb the rest of us. Would rather tear his tongue out than confide in us most of the time, but knows we would listen & try to help in an emergency. He was very kind and helpful when his grandmother was dying, so would expect support if something happened to us, but would be a little bit reluctant to ask, as I know his childhood was overshadowed by his sister's difficulties.