Can I add someone’s name to the deed if they are not a co-borrower on the mortgage?
If you are asking whether you can grant someone ownership or partial ownership of a property when they don’t carry the mortgage on that property, in most cases (California bias), the answer is yes, because they are two different things.
You referenced the word deed, so there’s some question as to what you think you need. A deed is an instrument used to transfer or convey ownership of real property; a deed is used to turn your note (mortgage) into a lien (legal binding) to the home while you are still paying them back for the loan.
Title implies ownership, and that is probably what you’re after. Having a home with a mortgage means you own the home, but that there are other interested parties with a stake in that ownership (you know who).
In many states, a person can hold title to a property (and be an owner) while another person carries the mortgage (if any) on that property. This happens frequently in the case where, for instance, a working child takes out a mortgage on a home owned by a retired parent. The mortgage is carried by one person (who must be given title to close the loan), while the property is held along with another.
Most Title and Escrow companies can handle this for you. A Notary Public will usually know about this and make any documents you execute official with the county authorities.