You can add snapshots to a slide from your Snapshot library.
Do the following:
In storytelling view, click in the story tools panel.
The Snapshot library is opened. The date stamp and any annotations helps you to distinguish between your snapshots.
Locate the snapshot you want to add and drag it onto the slide.
The snapshot snaps to the grid. You can use the keyboard arrows to move it freely.
The snapshot is placed on the slide.