"You Da Man!" I added the lines you suggested (w/o the DLookup statement),
moved it to BeforeUpdate, and this is now responding exactly as I intended.
However, I seem to have created another challenge in the process.
If I simply go to a new record and enter nothing, then attempt to leave that
record (go back to a different record or close), I get a debug error "Invalid
use of Null" on the following line:
Mousing over indicates the value is, in fact, being evaluated as Null.
Being a textbox, I would think it would simply see as a zero length string
("") - but not sure if that makes a difference?
If I can't resolve it, are you okay with me including the full event code
for you to look over - may have been lost along the way in this thread...?