Idaho Code § 30-29-142: number of shareholders.

(a) For purposes of this chapter, the following identified as a shareholder in a corporation’s current record of shareholders constitutes one (1) shareholder:

(1) Three (3) or fewer co-owners;

(2) A corporation, partnership, trust, estate, or other entity; or

(3) The trustees, guardians, custodians, or other fiduciaries of a single trust, estate, or account.

(b) For purposes of this chapter, shareholdings registered in substantially similar names constitute one (1) shareholder if it is reasonable to believe that the names represent the same person.