Does a domestic partner have to be a registered domestic partner to be administrator of an estate?

First of all my condolences to you. In terms of an appointed administrator to your son's estate, here is the statute concerning appointment: 28A‑4‑1.  Order of persons qualified to serve. (b)       Letters of Administration.  Letters of administration shall be granted to persons who are qualified to serve, in the following order, unless the clerk of superior court in his discretion determines that the best interests of the estate otherwise require: (1)       The surviving spouse of the decedent; (2)       Any devisee of the testator; (3)       Any heir of the decedent; (3a)     Any next of kin, with a person who is of a closer kinship as computed pursuant to G.S. 104A‑1 having priority; (4)       Any creditor to whom the decedent became obligated prior to his death; (5)       Any person of good character residing in the county who applies therefor; and (6)       Any other person of good character not disqualified under G.S. 28A‑4‑2. When applicants are equally entitled, letters shall be granted to the applicant who, in the judgment of the clerk of superior court, is  most likely to administer the estate advantageously, or they may be granted to any two or more of such applicants. (R.C., c. 46, ss. 2, 3; C.C.P., s. 456; 1868‑9, c. 113, s. 115; Code, s. 1376; Rev., s. 3; C.S., s. 6; 1949, c. 22; 1973, c. 1329, s. 3; 1987, c. 357.) Marriages of the same gender are not allowed in North Carolina, so he is not considered a surviving spouse; however, the court can render his partner the administrator if it is in the best interest of the estate.

North Carolina doesn't have statewide domestic partner registration, it's only in two cities.  And the law allows an unrelated person to serve as the administrator of someone's estate.

However, your son's partner, even if a registered domestic partner, isn't entitled to any of the estate.  You might want to consider having an attorney represent you in this, to keep the partner honest.  One place to find attorneys in other states is our website, http://attorneypages.com