19 CFR §141.39

1. (a)
   1. (1)General. A power of attorney granted by a partnership shall state the names of all members of the partnership. One member of the partnership may execute a power of attorney in the name of the partnership for the transaction of all its Customs business.
   2. (2)Limited partnership. A power of attorney granted by a limited partnership need only state the names of the general partners who have authority to bind the firm unless the partnership agreement provides otherwise. A copy of the partnership agreement must accompany the power of attorney. For this purpose, a partnership or limited partnership means any business association recognized as such under the laws of the state where the association is organized.
2. (b)Change in partners. When a new firm is formed by a change in membership, no power of attorney filed by the antecedent firm shall thereafter be recognized for any Customs purpose.