I'm thinking of using a companion pass for a three person booking.

When pricing out the itinerary it all works as expected. I know the first traveler will be on the full fare.

Does anyone know which of the other two travelers is the "companion" and which is the other traveler earning full SQD?

Two of the three of us have SQD targets to make, while the other is just along for the ride on this one trip and will be fine to earn fewer SQDs.