I have a classic search with several filters. In my example, I have a filter based on a dynamic list showing all regions of France (stored in the database). I'd like to add a first default item to the list: "All regions from France Metropolitaine". Regions are basically the catid field of a seblod content type. Then, the value of this first manually added item would probably be comma separated catids.
I presume I should use Seblod Events to add this to field, but I don't really know which one I could use.