Maybe see it from your wife perspective, If they start doing the laundry elsewhere the visit frequency will be affected. If you were ok with the sister doing the laundry when she was single then the fact she is married now shouldn't make any difference. Your wife is getting quality time with her sister and that is the important part of that arrangement. So try to be flexible, you arent doing it for the sister or her husband, you are doing it for your wife. And they aren't freeloader because they even offer to pay. — Juan Carlos Oropeza 59 secs ago