Question about merged tickets

I know this will eventually be solved by hierarchical tickets, but for the
time being, I need to figure out a solution and I’m wondering if anyone has
run into this before. Currently, when we receive two requests about the
same issue, we merge the tickets. The problem we run into is when one of
the customers calls us back and references the merged ticket number, if we
enter it into RT we get a blank request with no transaction data, not even
a reference to the ticket it was merged to. Normally, we can find the
ticket by searching around a bit for the merged ticket, but its sort of
time consuming. Has anyone come up with a solution to this? Something
where when you enter a merged request # in the “Display request #” box it
takes you to the merged ticket? Any thoughts?