As per the process, when the recommender/applicant submits the request or the post-acceptance section(s) with a linked question, then the master question (First Name field from the Applicant Information section) will get locked so that the applicant can't edit the answers which were sent to the recommender(s) as it avoid any confusion.
In this case, you can release the request section (which contains the linked question) back to the applicant for updating the first name field under the Applicant Information section and then re-request the request section(s) back to the recommender(s) to complete the section with the updated information.