You have dibs list. Each class signs up on the list for raids. The list is assembled with a high to low order. When you on top of your list you get dibs on the item drop. If you pass on an item, it gets rolled like normal with whoever is present and you stay on top of the list. If you take the item you then drop to the bottom of the list and the next person steps up. New people to the raiding list automatically start on the bottom. If the top of the list is not present during a raid, that individual gets temporarily bypassed and the the next person on the list gets dibs. When they return the remainder of the list may have changed but they remain on top until they decide to take an item.
The initial order of the list can be determined by a group of us rolling for a useless item. Your roll number will determine where you are on the first list. Also new people joining at the same time would use this random roll to dtermine thier order on the bottom of the list for fairness.
Let me know what you guys think
HarryLongrod