An employer may enroll in a group only if:

(1) We determine that the risk classes appropriately assigned to the employer are related to the industry category selected by the sponsoring organization for the group;

(2) The employer shares common ownership with an employer enrolled in the group that satisfies the requirements of subsection (1) of this section; or

(3) The employer has been a member of the group since prior to July 25, 1999.

In evaluating whether an employer's risk classes are related to the industry category, we will consider only those risk classes that define the nature of the employer's business operations insured with the state fund.