25 CFR § 162.230 - Can an agricultural lease be amended, assigned, sublet, or mortgaged?
(a) An agricultural lease may authorize amendments, assignments, sub leases, or mortgages of the leasehold interest, but only with the written consent of the parties to the lease in the same manner the original lease was approved, and our approval. An attempt by the tenant to mortgage the leasehold interest or authorize possession by another party, without the necessary consent and approval, will be treated as a lease violation under § 162.251 of this subpart.
(b) An agricultural lease may authorize us, one or more of the Indian landowners, or a designated representative of the Indian landowners, to consent to an amendment, assignment, sublease, mortgage, or other type of agreement, on the landowners' behalf. A designated landowner or representative may not negotiate or consent to an amendment, assignment, or sublease that would:
(1) Reduce the rentals payable to the other Indian landowners; or
(2) Terminate or modify the term of the lease.
(c) Where the Indian landowners have not designated a representative for the purpose of consenting to an amendment, assignment, sublease, mortgage, or other type of agreement, such consent may be granted by or on behalf of the landowners in the same manner as a new lease, under §§ 162.207 through 162.209 of this subpart.