Auctria requires that each bidder has a bidder# associated with them.
Multiple bidders can share a bidder# and in this case they are said to be linked. See Sharing Bidder Numbers for more details.
The system will automatically assign bidder#'s when people buy tickets or register online. This can cause problems for events that want to hand out bidder#'s at check-in.
In this case the best approach is to set the system to assign a high bidder# automatically. This is done on the Auction Details page.
If all the auto-assigned bidder#'s are at (for example) 1000+ then you can easily reassign the numbers at check-in using the Check in Bidders page. You can also tell at a glance if bidders have checked-in by their number.
A related approach would be to renumber all bidders using the Renumber Bidders page to have a high bidder# before check-in and then change the numbers as before.