Based on this post :
I'd like to be able to sort the related records in the pop-up based on field that is not OBJECTID.
For example, I have a point feature class which participates in a 1:M relationship with a table.
The popup is set up to show the related table.
The issue is that the records are displayed according to OBJECTID (That is, the record for 2012 was created before the record for 2011).
This is generally not a problem, but my users rely on that layer and expect that the last (or first, whatever) record returned in the pop-up is the most recent date.
Please let us sort related records in pop-ups.