Yes, during lunch they will seat people and fill up the tables fully, so saving seats for trading package attendees unfortunately won't be possible. However, once trading boards open, most all attendees stay in board lines the entire time so there will be lots of table space free. I for one will be using the table just as a holding place for my event goodies, so there should be room for trading package DPFers to join at the table.
Because they seat as people enter, all of us DPF Sweetheart package holders should plan to meet up together outside of the room by about 10-15 minutes before doors open so that we can go in together and be seated together.