Scanning multiple pages to create a single document is essential to a smooth workflow. InstaPDF has been designed for multi page scans from the beginning. Simply tap the middle PagePlus Icon from the toolbar menu. You'll then be able to add a page from your photo library. 

In case you need to re-order the pages, press and hold a page. You'll then be able to rearrange by dragging it to the appropriate position.

To delete a page, tap the red PageMinus Icon that will appear from the second page onwards. The first page cannot be deleted, tap Cancel in this case.