Prior to the effective date of the policy, the controlling insurer shall cause the controlling broker to deliver written notice to the prospective insured disclosing the relationship between the broker and the controlled insurer, except that if the business is placed through a subproducer who is not a controlling broker, the controlling insurer shall cause the controlling broker to retain a signed commitment from the subproducer that the subproducer is aware of the relationship between the insurer and the controlling broker and that the subproducer has notified or will notify the insured. [RR 1991, c. 2, §94 (COR).]