Hey Javier. Thanks for the note here; it doesn’t look like that’s doable from within the basic slug editor on the Event entry, but I’d wager there is a way to do it somehow. Not positive but let me ask Jonah (who is more knowledgable about such issues than I) to take a look and respond directly. If he can’t I’ll try to bring in another dev who can. Stay tuned!
Unfortunately changing the structure of the permalinks within our plugin is not very easy at the moment. Hopefully this will change in the future. For now you’ll need to work out some alternative solution, possibly some rewrites which is beyond what we can help you with. Sorry I can’t offer up more here. Good luck!