We have a client who's currently using Bookly within WordPress, but they're interested in migrating the functionality portions of their site to Invision. The calendar does most of what they need, but the one thing it lacks is preventing overlapping events in the calendar.

Is it possible for the Calendar to do this? Where would I begin to look to build this out? We just need a message to pop up saying their event conflicts with an existing event in the same calendar. We'd be willing to pay for the development if there's a good path forward, but suggestions or pointers are very welcome.

Bump. Any ideas?

Is there a better place to post my question?

Anyone?

This is not possible with the default Calendar.  It allows open appointments that can overlap.  

You can reach out to the Providers list or post in customization request.