Authorized User Accounts, Do they work?

My boyfriend and I trying to purchase a home together. We have paid off all of our collections and paid down our two credit cards. I am 14 points away from qualify for a home loan. We both need a 640 credit score. My mortgage broker suggested having a family member or friend add me as an authorized user to one of their credit cards to give me those extra points. Does this really work? I am kind of embarrassed to ask someone to help me so before I do I want to know if it is worth the trouble.