I agree with everyone else -- just say no! She may say she's going to pay rent but with no job where is she going to get the funds, the money fairy? Not to mention that your electricity, water, etc bills will be going up with another person. If any of the other relatives give you grief, tell them you will be dropping her off at their house and they can take her in. If she wants a reason, tell her "we let you live with us before and a good time was not had by all".