Legal Question in Real Estate Law in Maryland

Re: Do I have any rights?

You present a classic problem that often occurs when family members undertake what is in essence a partnership--and don't formalize it by any writings. There is perhaps an implied obligation among the co-borrowers to contribute an equal amount to curtail indebtedness, but this isn't necessarily a hard and fast rule. If you want to keep the property, you need to either formalize your agreement with the grandmother or try and buy her out. At the very least, keep good records demonstrating that you are making the payments to the lender, so if down the road you sell the property, you can document your claim for a greater share of the sale proceeds.

Of course, it the deed says you own the property as "joint tenants with right of survivorship", you and your husband will become the sole owners when his grandmother passes. If instead it says you own it as "tenants in common", her share will pass through her estate at that time.