I think if your parents are ok with it, then continue on with your plans. His brothers sound like a pain in the @ss. I would not change anything just so they could be included. You said they invited themselves, but have they booked? I say stick to your guns and do what you want to do. Do the AHR if it will be something that the both of you would enjoy. Is your family planning on attending? This is what you both want and will be the most happy with. The others will get over it!