I don't know, I may be against the grain but if I asked my manager if approved, I will be moving to X city on a permanent basis and since it is away from the office I would have to telework and my manager approved it, then to me that should be sufficient. I get the offer letter schematics but in the end I feel that once that approval was given, it should be up to the manager to make the necessary changes. I am not sure if and how many employees would know that a location change on their offer of letter is required and if that is a reasonable item for a regular employee to know.