Originally Posted by BertieBadger

If you are all travelling in the same cabin using just one 241 voucher, you should be able to just put them all on the same booking.

A 241 booking is not limited to 2 people, it's just that the 241 is only applied to 2 people in the booking.

To make that explicit, lets imagine it was 100,000 Avios per passenger?

2 passengers without a 241 = 200,000
2 passengers with a 241 = 100,000 (because you get 2 for the price of 1)
4 passengers without a 241 = 400,000
4 passengers with a 241 = 300,000 (because you get 2 for the price of 1, plus 2 at regular cost)

Does that make sense?

So, if you want 4 passengers total, that's what you need to search for. Once you find the flights, you can apply the voucher, and it should remove the remove the Avios cost of 1 person