Question Maintaining IDs from an existing hardcopy family tree

> However webtrees wouldn't accept the update - I can't post a screenshot here, but the entry widget showed a red border, but no error message.

Red border? As in the red border that indicates pending edits?

Is there a banner near the top of the page asking you to approve/reject the pending edit?

> I can't see any other way to edit 'REFN' other than through the Raw GEDCOM option.

Control panel -> GEDCOM tags -> REFN -> unhide.

Then just add the same as any other fact/event.

Thanks to commenters above for advice.

I have now added a REFN value via GEDCOM edit. However it shows up under Extra Information and only if user opens that drop-down.

See attached.

Any advice on how to show this more prominently, ideally near the name or under Facts and Events?

 

In the control panel you can configure to not show "extra information".
Whatever normally is displayed there will be put in the list of facts/events.