The answer is in the “who is an insured” section of the CGL form. The coverages of policy A and policy B will not interact in this instance.

If the named insured is designated in the declarations as an individual, he is an insured but only with respect to the conduct of a business of which he is the sole owner. And, the last paragraph in that section of the CGL form states that no person is an insured with respect to the conduct of any current partnership that is not shown as a named insured in the declarations. So, under policy A, your client has coverage only as an individual and the policy will not respond to a claim or lawsuit based on exposures covered by the other policy, policy B.

As for policy B, if the named insured is designated as a partnership, the members and partners of that partnership are insureds with respect to the conduct of the partnership's business. So if a lawsuit names both the partnership and each of the partners, policy B will consider all the named defendants as insureds.

As for an example when both policies would apply, consider this scenario: suppose the individual named insured on policy A is in the business of managing real estate, and that he manages a piece of property owned by the partnership, which is the named insured under policy B; suppose further that a claim arises based on the negligent management of the property. Will the individual named insured be covered by both policy A and policy B?

In this case, the named insured has coverage under policy A for his operations. Policy B also covers the individual as an insured due to his activities as the real estate manager for the named insured partnership. And since the individual is an insured under both policy A and policy B, the other insurance clause on the policies is invoked to direct the obligations of the insurers. If contribution by equal shares is permitted, each insurer will contribute equal amounts of the damages won by the claimant until the particular policy's applicable limit of insurance is paid. If contribution by equal shares is not permitted, each insurer's share is on a pro-rata basis.