Your comments
This current feature is available at the widget level which is great! But it doesn't match with the member portal/app.
Most of the time a request for a split payment involves a credit card. This is a good idea!
I second what Christy has said! We are constantly dealing with this exact issue and have tried to handle it in the same way but it's confusing and not working out very well.
Instead of Green when a check-in is confirmed, Red to indicate the no-show. It's just helps to differentiate.
Customer support service by UserEcho

Love the override pop up warning for events. This would be a great place to get the waitlist started. I realize my original suggestion was for adding people to the waitlist when a waitlist has already been started. But, still from the expanded scheduler, to be able to start the waitlist is what's needed in the first place, then the ability to add people to the waitlist. "Event FULL, Do you want to: OVERBOOK, WAITLIST, CANCEL". Adding registrants to the waitlist, if waitlist is available, is the next logical step after answering the question in the overbook warning.