At first glance, it sounds like this is the problem: you have your parents in the database more than once: The first thing I would check is the Individual list. See if your parents are listed multiple times.If they are, 'Merge' them, I am not too farmiliar with PAF, but I think you use the Match Merge under tools to make multiple listings of one individual into one listing. ( - but on further reading, I am not sure)
Are your parents listed an having married more than once? and hence multiple families? The more I read of the problem, the more I think you are right. "Your brothers are just trying to avoid you"
I would try "Edit" "unlink individual", and unlink from their parents, for each of your brothers, then add them to your parents again and see if that works.
I am only guessing, It sounds confusing. Good Luck, Alfred