Before moving them in, find out how much they were paying for rent/food/electric/water/etc etc and add that into you calculation if you choose to sling her a monthly wedge.
Met a nice lady... wanted to move in and me give her 15k a month lol.
With rent/electric/water/food her monthly outgoings were 9k a month....Told her that as she would now be pocketing that outlay instead of spending it I would give her 6k a month making up her total of 15k.
she told me to go fornicate with myself !!