43 CFR § 3837.23
How do I notify BLM that I have acquired a delinquent co-claimant's interests in a mining claim or site?
June 11, 2020
If you acquire a delinquent co-claimant's interests in a mining claim or site, you must submit—
(a) Evidence that you properly notified the delinquent co-claimant;
(b) An originally signed and dated statement by all the compliant co-claimants that the delinquent co-claimant failed to contribute the proper proportion of assessment work, expenditures, or maintenance fees within the period fixed by the statute; and
(c) A non-refundable service charge for a transfer of interest, as found in the table of fees in §3830.21 of this chapter.