@karebear1121,
Ok, let me see if I have this correct. You currently pay 802 for mortgage and 350 for all utilities. You need to add food to this, so lets say food for you and the boyfriend and your daughter will run 800/month (I'm going low with this estimate.) So he wants to move in and pay you $300 toward your $1,952.00 worth of expenses. Your brother pays you $400 simply for the use of a room and boyfriend figures he should pay less because he is sharing a room with you??? I think you should offer one of the following.
1. A 50-50 split of the expenses after deducting for your brother's contribution. This would amount to your boyfriend paying $776/month. And when your brother moves out he should split the entire amount with you, making his payment $976/month. (Maybe you could be nice and just keep it at $776 since your daughter is there part time with you.)
OR
2. Since he believes he deserves a discount for sharing a room with you, charge him the going rate each time the two of you have sex. I mean, fair is fair. He is getting sexual favors from you without the commitment of marriage, so you should be compensated for that, right?
Ok, number 2 was somewhat in jest, but only $300/month means he gets off cheap and down the road if the two of you part ways he will have built himself a nice little nestegg at your expense. And gotten laid regularly while doing so. Sweet deal. You might think he is not trying to get off cheaply, but he is.