My boyfriend and I have shared a residence for the past five years. We are also sharing the cost of renovating and maintaining our residence in Pennsylvania. He would like to add my name to the deed. How can we do this?

Depending on the mortgage lender and their rules, it may be as easy as having a quit claim deed done with both names on it ( thus he signing over 1/2 of the home) if there is a mortgage on the home, they may require a re-fiance for a new mortgage with your name on it also to do it.

I recently learned that a married couple in my family have an arrangement whereby both spouses are on the deed but only one is on the mortgage. It was the first I've heard of it but apparently this is possible.

Yes it is possible to have two people in the deed, and one on the mortgage, but normally this is done either at purchase or when they do a refi and one party gets it in their name,

Adding the name after thiere is a mortgage is not always as easy as getting a mortgage. Also the state, since home ownership and how the name is added on the deed can all matter.