We have one room which is 3 degrees cooler than the rest of our home during the winter. I have closed one small register in the adjacent walk-in-closet, and one small one in the adjacent bathroom to take the edge off in that bedroom. We have an electric HVAC and heat pump with 17 total registers. I understand that closing too many registers can cause damage, but what about 2 out of 17? Thanks for any advice.