Originally posted by ecoutez
Pick a new name for your copy of the bluelagoon theme and copy it:
cp -pr /usr/local/cpanel/base/frontend/bluelagon /usr/local/cpanel/base/frontend/mythemename
I found this confusing also, but let me clarify just slightly. Ecoutez is saying to simply copy the *folder* with the themename, giving your new folder a new name. I think that's what he's saying.
The WHM seems just to look at the names of the folders in this location when it's figuring out what themes you have installed.
If you've made a copy of the bluelagoon folder and named it reallybluelagoon, then WHM will allow you to select the reallybluelagoon theme, make it the default in billing packages, etc.