Hi,
In “Related Types” tab of Settings / WP Related Items (WRI) menu, you will find sections for all of those post types for which you have set that would like to use in WRI.
You can set in these post type sections which categories should be used for that specific post type.
Usually one category is enough that is selected by you as a “common” category, and this selected category type can be selected for all of your post types.
This functionality is available in PRO version only.
Peter Rath
WebshopLogic