Most mortgages do not allow the addition of deletion of names because the names associated with the mortgage are responsible for the repayment of the note.
Even in the case of divorce the only way one party can be removed from the mortgage is for the home to be refinanced under the name of the party who received the home in the divorce settlement.
My suggestion is for you to have your name added to the deed of the home. This way should you inherit the home you could "refinance" the note instead of "purchasing" the home. You can use a legal instrument called a "quit claim deed" to put your name on the title. Consult your local title agency or attorney to process this document.