your case is seems to be different. your parents have only threats because of 498a, in DV only husband is respondend, Hope your brother and his wife is not staying with your parents, if not ask them to stay seperate from such greedy people. even If your Sister in law files 498a on you conviction is merely possible in your case. and even if they give some proof to prove you brotehr will also surely landup in his trap only.
as counter attack your parents can ask for maintenance under CRPC 125. so all in all you or your parents need not to worry about it.
Thanks and Regards