Guideline for Editors in case of Request for Adding Authorship After Publishing of an Article
When an author requests the addition of another author's name after an article has been published, the editor must first determine the underlying reason. If convinced, the editor should obtain written approval from all concerned authors for adding the extra authorship. There are two possible outcomes
All concerned authors agree to include the additional author and provide written approval
The editor proceeds to complete the journal's formalities with the new author's assistance.
The editor updates the author list with complete details and publishes a corrected (revised) list.
Some or all concerned authors disagree with the inclusion of the additional author
In this case, the editor must express their inability to make the requested change unless all authors reach an agreement.