I have a return booking for 2 adults and 1 infant from LHR to AGP in CE booked using a companion voucher. We have already used the outbound, however now want to travel separately on the return leg, 1 adult on this original flight and then 2 adults (1 from original booking and 1 more) and 1 infant on another date.

What’s the most efficient thing for me to do, all the flights we would want to take have CE avios availability. Can I apply for a FTV for just this return leg, given a Companion Voucher was used, or is this pointless, how does it work in this instance?