Unknown field for recital

I would really love to see a dropdown box with the three options of unknown, yes or no for recital participation. I previously used Studio director and all student's recital field was a drop down. The default position was "unknown". This enabled us to who we hadn't heard back from about recital performance or that we needed to get our "commitment" for to or follow up with about the show.

Similarly, I wish I could run a report that let me know filter by who was or wasn't participating in recital. Also, who was unknown?