How do you change a reunion registration? Specifically if they ordered certain items for sale?
Is there a way to update the numbers of those items (i.e. change 2 reunion tickets to 1 ticket)?

1) Click Reunion Planner
2) Click the icon under your Attendees column to enter Edit mode
3) Click on the name of the Classmate you wish to edit
4) Click Edit Items
5) Adjust quantity as desired

What if they never placed an actual order for tickets but they did put the number of attendees? I can see they put in a party of two but they never entered that in for the number of tickets to be ordered giving me a $0 for what they owe.

The Classmate has to go back in and actually order a ticket then. Unfortunately you are using a store in what we called "Reunion Planner I." Everyone starting reunions now is automatically in the new "Reunion Planner II" store which solved that issue and a whole lot more. But, in your case using the original store, that's not going to help you... Thus, you'll need to ask the Classmate to go in and order tickets.

Not a problem, luckily it is only 4 of them. Thanks for the response!!

Is there a way for a Classmate to edit their order to increase, or decrease, their ticket purchase?

Thanks!

A Classmate can increase his or her order by ordering more stuff, yes. But a Clasmate cannot "unorder" something already ordred. For that, the Classmate would need to contact an Admin, and an Admin would need to initiate a refund.