I have booked for four people using a single GUF2 and an Amex 241 on a single joker redemption - total in F was 350,000 Avios. Two at 100K, one at 150k and one at 0. Done the same in CW for 250k for all four of us too.

So it would seem that a single joker can have the GUF2 applied to it for two persons, and the other two on the OP's booking pay the full rate of avios.

As a suggestion to the OP, if you are going to Africa your flight will probably be overnight, my view is that F is a waste of avios/money for an overnight flight over the CW product. YMMV