Hi @lisa-wilson1111
I’m afraid this is hard to achieve, especially if you have a lot of entries in the list. That’s because ACF uses pagination for the list and will load more entries using AJAX automatically. If you want to do it, please take a look at this page to learn how to use Javascript with ACF: https://www.advancedcustomfields.com/resources/adding-custom-javascript-fields/.
Another easier method is to update the list on save. This means that the entries will be added once you saved the contents and reloaded the editor page. You can use the true/false so the user can choose if they want to add all of the entries and then use the update_field() function in the acf/save_post action hook to add them.
I hope this helps 🙂
