You may want a collage page for each class or grade. You will need to add blank pages in Portrait Auto Flow so that you can create pages in between the portrait pages.
Adding a blank page within Portrait Auto Flow is used when a single page is needed on one side of a portrait page spread. If you want a blank page spread (2 pages) in between portrait pages then use Add Pages in the yearbook overview. This article will tell you how to add page spreads:
1. Log in and select Yearbook.
2. Select #4 Auto-Portraits to get to Manage Portrait Auto Flow.
3. Select Add Blank Portrait Section.
4. Blank sections are always added as the first section.
5. You can click on it and drag it to where you want it. You can also Rename or Delete the blank page.
6. Make sure the sections are turned on and then Close & Update.
7. Now you can see the blank page inserted in the auto flow pages.
Using AutoFlow Video Tutorial: https://treering.zendesk.com/hc/en-us/articles/200017315-Portrait-Auto-Flow-Video-Tutorial