Where things get bothersome is home maintenance and improvements. That’s equity responsibility. So I believe one has to determine if B is equal to a roommate paying rent; in which case, the financial burden and yes the fun decisions are A’s to make. Then utilities. A should provide the past years usage and payment. Can the increase be attributed and paid by B? Then food/chores. And as any good attorney would ask A, would you feel differently if B won the lottery?