TMEP § 503.07
The USPTO does not process requests for "indexing" or "cross-referencing" additional trademark registration numbers or application serial numbers against a document previously recorded in the Assignment Recordation Branch.
Therefore, even when an assignment document (or other document affecting title) has already been recorded in the Assignment Recordation Branch in connection with a trademark application or registration, a party who wants to record that document against additional applications or registrations must submit the following:
The USPTO will assign a new date of recordation for the additional applications or registrations, update the Assignment database, and create an electronic record of the cover sheet and assignment document (or other document affecting title), which will become part of the official record. See 1157 TMOG 12 (Dec. 7, 1993).