Triggers, keeping two files synchronized, record locks

I'm trying to keep two master files (customer files from two vendors)
synchronized by having "after" triggers on each file add/update/delete the
other file.  Using the defaults on ADDPFTRG, I'm getting hung up with a
deadly embrace.  Here's what happens:

1)  Application program updates file "A"
2)  File "A" rewrites the record but *does not release the file "A" record
lock*
3)  File "A" trigger reads file "B" for update
4)  File "A" trigger updates file "B" but *does not release the file "B"
record lock*
5)  File "B" trigger reads file "A" for update...and since the file "A"
record is already locked by another program, the trigger hangs.

I've solved this one before but my advancing years prevent me from recalling
my solution.  It looks like changing the trigger update condition to
"*CHANGE" will prevent triggers from executing when no change has taken
place.  Or am I missing a parameter or coding technique that will resolve
this?

Thanks,
Reeve