how can I create an Upfront child theme like the ones you

Hi,

how can I create an Upfront child theme like the ones you provide (Spirit, Fixer, ...). At first I want an almost blank theme so that I don't have to edit a provided theme whenever I create a new theme from scratch.

I'd also like to create ready-made themes based on the Upfront builder and enable them in my multisite-installation.

My guess is I could "just" copy a theme in the themes-directory of the WP-installation and edit it - but I'm not sure if this leads to conflicts...

Thx,
Raib