To answer my own question, and in case this helps anybody, it does appear that TAP released 9+ award seats for a flight, but they could be booked in only one reservation/PNR. In other words, for example, booking 2 of the 9+ seats in one reservation immediately wiped out the rest of the inventory. That made it impossible to book a family using two separate mileage accounts. This was a first for me, given that we ordinarily see award inventory on a flight go seat-by-seat. (My evidence for this is that I saw it happen as detailed in the post above, then I canceled the reservation, the 9+ awards came back, then I booked 4 seats, and the rest of the inventory again disappeared.)