The F1 Groupfinder #2  Template uses small groups #2 from our layouts site and uses groups populated from Fellowship One. 

Content > Link Lists > "F1 Group Categories"

The category list pulls from the “Category” field within F1, but the link list within the CMS will allow you to manually control which categories display in the dropdown. Within each item, the "name" field is used for the category title, and  the "description" fields need to have the corresponding category ID.