Move an existing Wikipage to be a sub-page

Move an existing Wikipage to be a sub-page

I was wondering if there's a way to move an existing wiki-page to be a sub-page?

We started creating wiki pages, but as pages built up we'd like to assign sub-pages to categorize our wiki. However, I can't seem to figure out a way to do this.

Thanks for your help,
   -Duncan