Somewhat easy? That depends, do you want to show the Venue and the Sub Menu in separate select fields or would you want to display them the way you listen them above with the select field containing these items
- Covent Garden > auditorium
- Covent Garden > Patio
- Covent Garden > Hallway
The latter would be easier than the former:
http://www.advancedcustomfields.com/resources/dynamically-populate-a-select-fields-choices/
You can set the value to the sub venue ID and the label to what is above.
If you want them in separate select fields than you’d need to create your own javascript and ajax to detect when the first on changes and update the second field. While possible, far more complicated.
