Hi Jim,

In that case, use an IF test to determine which MERGEFIELD to use. For
example:
{IF{MERGEFIELD PO_Box}= "NA" {MERGEFIELD Address} {MERGEFIELD PO_Box}}
Of course, you'll need to decide which address to use if you've got both
(the above gives precedence to the PO Box), and you might also need to allow
for both the PO box and the actual address to span more than one line.

Cheers