How to switch from nonfiction "one part" to nonfiction "two part" mid-writing?

I started a nonfiction project as a one part nonfiction but realize I want it to be a two part book. What is the easiest way to transfer all my material into the two part format?
I’m a newbie to Scrivener… I appreciate your help!

Just create one or more “Part” folders in the Binder. Drag the existing material into them.