You must have a certain number of "points" added up in Dinan parts to be certified for it. Each Dinan part carries a "point" value.. some items are 1 point, some are 2, etc.
To get a Dinan badge, you have to accumulate 10 points' worth of parts. Here's a breakdown of number of points assigned:
https://www.dinancars.com/the-dinan-badge/