Prevent duplicate item on same date

Prevent duplicate item on same date

Hi! When I am adding a new record, I would like my dropdown menu (that is in the form) to grey-out the items that are already recorded on the same date as the field in my form.

In other words, I would like to prevent an item being double-booked on the same date. How do I do this?


I would like for the dropdown of "Facade" to grey out any other items that are being used on the same date. The date is in "Date of Event".
I should also mention that "Facade" is a lookup field.