The people who didn't attend your reunion are important to your family, too. They may have had to work, lived too far away, or had car problems that kept them away. But those aren't reasons to exclude them from the fun and comradery of your family reunion. You can help them feel they're part of the family by sending them something after it's over.
What are some of the things you can send?
You don't need to send all these things, of course. The idea is to remember people and help them feel loved. It takes time to follow up and involve family members after the reunion, but you have spent a lot of time and effort to tie your family together thus far; isn't it worth it to get all the value you can from your efforts?