Each brewery which enters into an agreement with a beer wholesaler shall designate a sales territory for that wholesaler which is applicable to the agreement. No brewery shall enter into any agreement with more than one beer wholesaler for the purpose of establishing more than one agreement for its brands of beer in any territory. However, the existence of more than one such agreement as a result of a sale of a brewery as contemplated by § 4.1-504 shall not be prohibited. Each brewery shall notify the Board in writing of all designations of sales territories, the identity of the wholesaler appointed to serve such territory and a statement of any variations which exist in such designated territory with regard to a particular brand. Redesignations shall be reported to the Board within thirty days.