We've inherited care of a WP Networks install with many individualized sites. Most of them have some type of directly customized theme. If I begin updating themes, clients will lose customization. We've since disallowed direct theme customization; opting instead for child themes. Going forward we'll be okay; however, I need to tackle these legacy sites.
How might I update themes in place and at the same time save and/or re-implement clients' customization? I will need something that I can automate at some point.
My first idea was to download the currently running version of their theme from a codeplex and do a diff across both folders. Next activate that unaltered version in the unaltered theme and moving the diff'ed files to a child theme. Once that is in place, I'll issue
wp theme update --all.
But I still fear this will be a load of manual work.