I'm at a point where I'm tired of dealing with my ex-husband and his mother about this. DS is 28 - he has a very good job and he makes a lot of money. He has a lot of disposable income. He also likes to live a bit lavishly (his flat, his car, his clothes, holiday destinations, etc).
DS' dad and grandmother are constantly on his case about this. They say he should be much more frugal. And while I don't entirely disagree with them (buying a 800 quid bottle of wine is a bit too much) I don't think I can dictate what he do and what he shouldn't do with the money he earns. Last week, DS' dad outlined a monthly financial plan that he gave DS, and demanded he stick to schedule he outlined. They fell out over it. My ex-MIL called me and told me I should convince DS to follow his father's financial plan. I told her it's not my place to give DS a minute-by-minute plan on how he should spend his money. She said I was being unreasonable and that I was a "bad mother." I cut the phone.
I've spoken to DS before about the importance of financial security not only now, but for the future too. But I don't think it's my place to outline a minute by minute report on how he should spend every penny he makes. DS worked extremely hard at school and uni to get to the point he's at in his life. From childhood, his head was always buried in books. Of course he's my son so I'm not exactly going to be entirely objective, but I've never come across anyone as intelligent while also possessing a limitless work ethic. I figure he's smart enough to take care of himself - he's gotten this far.