Yes, it's supposed to be 3 per passenger, however, I had a hard time with it when I tried last Oct. I called to make the reservation because one ticket had a special handling and the rep didn't know how to do more than 3 on a reservation. But the website is very clear that it says "3 per passenger" and before that it said "3 per ticket"... nothing about a confirmation number or reservation and you can have multiple tickets on a reservation/confirmation. But she didn't know how to do it, so I bought the one ticket from her and then bought the other online myself and we just flew on different confirmation numbers.
With the report from
@belle032 I'm very interested in how they did it so I can just do that next time, if it ever comes up.

For me it's probably unlikely but we had a Luv voucher, plus a gift card for each one of us that didn't fully cover the ticket so it would have been 5 forms of payment any way I sliced it.