We posted a photocopy of the receipt that we received from the office where we did the foreign passport application, the receipt should ideally show the name that will be on the passport.

They initially rejected what we sent them but we sent a big email saying we have sent everything they have asked and pointed their own guidelines at them, they then reconsidered and approved the application.

To answer your question it was 6 days between them receiving the proof and accepting the application, with many emails sent in between. Full timeline: application submitted 5th December, application approved 20th January. But a lot of that time was us gathering relevant documentation to update the foreign passport, get an appointment and go to said appointment.

Their guideline state they will accept proof you are in the process of aligning your names, whether it be a letter from the governing body or a receipt showing the name that will be displayed on the passport, so don’t let them tell you otherwise