Roommates

I don't know if it's a glitch or not, but all of a sudden there have been a surplus of roommates showing up at my house and I have no clue how to make it stop.  Initially, my sim asked one sim to be a roommate - the details of which I didn't realize, I thought it was like moving in, my mistake - and now that she actually lives with them - like I have control of her and everything - other sims keep turning up in my house.  I keep just shipping them off to live with others via the lovely Edit Town mode but I would prefer it if this stopped happening.  I'm sure someone here has to know what to do!