That is a good question because my husband just lets his teen kids do what they want and me only being the stepmom, I can't set any rules around the house. One is 18 and one is 16, but as long as the 18 year old is living in our house, I think we have the right to set rules. I will be interested to see the answers hat you get and maybe they can help me too.
Well you can explain that they are his kids and it is his responsibility as a man and father to raise these boys as best he knows how. They need a good male figure in their lives, also for their own future as fathers and husbands. Explain if they don't following the rules which you intend to enforce if he isn't going to you will, as it is your home as well as his. You have that reaponsibilty if he won't you will.