Howdy Annelies,
It would be my pleasure to assist with this as best I’m able.
WordPress does not natively support breadcrumbs. In fact, WordPress posts are not hierarchical, meaning that anything which does try to add breadcrumb support to WordPress will inherently be broken in some ways.
All that said, I have seen some third party plugins add breadcrumbs with decent success, they just rely on you to not do anything that will break stuff. You will have to consult the documentation of whichever breadcrumb you are using in order to modify it. I have absolutely no idea how to modify this third party software. Fortunately, events are a standard “WordPress Custom Post Type”. It is likely that your breadcrumb plugin or theme has instructions for modifying the behavior of a “CPT”, and that generic instruction will apply to Event as well any other post type.
Does that all make sense? Do you now know where you can begin searching for some instructions?
Cheers!
– Brook