Correct +1.
This happened to me once as a plat. Two of us were traveling, but there was only one seat available for upgrade. TA told us we could split the PNR and I'd get it, but my wife would be left to fend for herself. We had exit row seats so we stayed in the back.
We were also told that the adding to the list didn't apply to web check in at with 2 or more on the PNR.