The award is for 7s staff that contributed significantly to the achievement (within 5 months). Typically the easy way of telling is to look at who was part of the staff when the requirements were fulfilled. With that being said, we won't turn down nominees that were active 7s for most of this period either.
Really, we just need a witness verification not only that the members and time is correct, but also that nominees are eligible through rank at the time of achievement.