I am so sorry. I'm on your side - I don't think your mother should be letting some guy you've barely met move in, especially when the motivation for him moving in is desperation rather than a natural progression of their romance.

Nothing you say is going to change her mind about this. You might try talking to some of her friends or a relative she trusts --- someone who could point out how dumb it is to let a man you don't know that well move in with you and your 16 year old daughter.

Unfortunately, until we are 18, most of us have to suffer through our parents bad choices and decisions we don't like. You only have a few more years, right?