Idaho Code § 15-3-111
In cases in which a marital community has been dissolved by the death of either spouse at any time, the survivor was then entitled to all of the property of the decedent by will, law, or both, and the survivor died before any proceeding had been commenced for the probate of the estate of the spouse whose death occurred first, the estates of both decedents may be joined for probate in a single proceeding in any court having jurisdiction of the estate of the spouse whose death occurred last. The three (3) year provision of section 15-3-108, Idaho Code, applies only to the death of the spouse whose death occurred last. The initial application or petition filed in any such joint proceeding shall contain a statement of the facts upon which such joint proceeding is based, in addition to all other statements required by this code to be made therein.
Idaho Code § 15-3-111