I have two project A & B having a common field 'DRN'.
In Project A, if any an issue's DRN field is added/edited, it should look for DRN field entry in Project B. If found, then related issue of Project B should link automatically to Project A ''Linked Issue' field.
Thus, we'll be able to track from Project A issue, any related issue if exists in Project B based on common DRN filed entry.