You have 4 comp upgrades. Depending on the tickets this could translate to 4 upgrades on 2 separate flights (equals 8, as you say) - but usually only 4. But the key is having the appropriate inventory available, just because there are 'available' or 'empty' seats in business does not necessarily mean they are available to use for the comp upgrades. It may be too late in this instance, but when wanting to use comp upgrades I always make the booking online up until the last step then ring the velocity number and ask if the upgrades are available on those flights and can they process them for me on the spot. If they say yes, I then 'pull the trigger' on the booking (while the agent is still on the phone), give them the reference number and they process the upgrades.