Notice: this information was written when Microthemer version 2 was current. On Dec 26th, 2014 version 3 was released with a completely new interface. Some of the information may be redundant, but as much of
the functionality remains the same in version 3 we haven't deleted this post.
I have a few installs of Microthemer and realized that as my themes develop my microtheme also develops. The installs I have are all on the Artisteer core so I develop my themes – micro and main – on a single install. So then when I wanted to upgrade all the other microthemes without losing their current per site settings or edits, would I just replace the config.json with the developed, newer version?
End result being the interface would have the new edit areas available, but the current edits would not be affected.
I don’t think you’ll be able to automatically update the micro themes without losing your per site edits. If you update the config.json and then re-import the theme you will wipe any existing edits. The config file contains all the selectors and the edits.
It sounds like you want to add the new selectors you create in your development area to all of your other installs. But unfortunately there’s no way to do this automatically that I can see. You would need to update them manually.