Hi @alexg
I’m afraid you need to use advanced JavaScript code to do that. Also, please keep in mind that ACF uses Select2 library.
If you think it’s something that ACF should have, could you please open a new ticket so your request can be passed to the plugin author? You can open a new ticket here: https://support.advancedcustomfields.com/new-ticket. Also, please don’t forget to explain your request again.
Thanks 🙂
