You can create groups of slides in the slide navigator by indenting them up to six levels deep. Grouping doesn’t affect how a presentation plays, and it can help you organize and arrange slides more efficiently. You can move grouped slides as a set and collapse groups for a better view of your presentation’s organization.
In the slide navigator, select one or more slides you want to group under the slide above.
Drag the slide to the right until a line appears on the left.
You can indent only one level between consecutive slides.
To ungroup slides, select one or more grouped slides, then drag them to the left until they’re no longer indented.