Ask them how much more they need for the deposit, lend them the money (on the basis that you won't see any of it back), move them out and then downsize so that there's no room for them to move back in with you and they will have to fend for them selves. I've got two kidults at home living for free and can I get rid of them....
When you pay at supermarket fuel pumps
DON'T assume your landlord covers you
Incl £2ish sun cream & £1.50 disposable BBQs