Fixed....thanks for the replies.
After replacing the passenger switch, the problem was still there (not that I thought it would be that easy). I pulled the overhead cluster to get the part number and found that it was around $95 -- better play w/it some more first.
So, I searched for the threads you referenced, but couldn't seem to find any that described similar behavior. But, they all mentioned the driver's door controlling the warnings and buzzers. On a hunch, I replaced the driver's side switch. Presto! Everything works properly. Of course, I had to replace the modified passenger switch as well, so I don't know if both were faulty or not. I ended up replacing all 4 switches for good measure.
Live and learn...
Holly Springs, NC