It’s not possible to create grandchild themes in the same way that you create child themes, but you can use a plugin to dequeue/enqueue stylesheets and scripts, and also override the locations of the main query templates.
It’s obviously not the ideal solution, but there are cases where it may be the least-bad one.
I’ll be giving a presentation on building Child Themes at the Seattle WordPress Developer’s Meetup tomorrow. You can follow along with the presentation if you plan on attending.
Mark Root-Wiley wrote a great article on the pros and cons of using premium themes, writing child themes and writing themes from scratch. It’s discussed in the context of WordPress themes, but most of it is applicable to other CMSs as well. I think it’s a good introduction to give clients when discussing which method […]