Board Thread:Support Requests - Getting Technical/@comment-9605025-20150628052603/@comment-24473195-20150628223934

Basically, you can add a particular hidden category to all pages that are part of your main category (and its sub-categories). Then you can set it as a hidden category, so the category will not appear on the page itself, but will still exist, and every edit made will be attributed to that  hidden category.

For example:

Page 1 - sub-Category 1  → Hidden Cat (good stuff)

Page 2 - Sub-category 2 → Hidden Cat (good stuff)

If user A edits sub-category 2, (s)he'll also end up editing something in category "good stuff". So it will register as an achievement.