We have linked bookings with others and all have premier. The app let us book one speciality for all of us, no charge but wouldn’t let us book another one except individually without charge. Good news, I got on chat and agent Mary, who was awesome, and booked us a table together without charging using all our speciality dinner credit.
You might try chat on the app. I know it’s a hit and miss but that’s twice now they have been very helpful.