I didn't move out until I was 21, but Mum had a hard and fast rule for all us kids. She would support us financially as long as we were studying. If we finished or dropped out, we had to pay board or move out. I don't know if you've mentioned similar ground rules to DSD.

I think share houses are a great (cheaper) way to start. Yes there are problems, but that's part of growing up and becoming an adult.

It will be interesting to see how things go between her and her friend if they do manage to move out together - nothing like living with other people's mess to help you appreciate things at home