The surviving spouse or domestic partner of the decedent, a relative of the decedent, or a relative of a predeceased spouse or domestic partner of the decedent, has priority under Section 8461 only if one of the following conditions is satisfied:
(a)
The surviving spouse, domestic partner, or relative is entitled to succeed to all or part of the estate.
(b)
The surviving spouse, domestic partner, or relative either takes under the will of, or is entitled to succeed to all or part of the estate of, another deceased person who is entitled to succeed to all or part of the estate of the decedent.