Count Items in one board group in another board?

I have an Event board that has events that we’re planning organized by groups (e.g. Inwood Hill Park Event is one group and Pelham Bay Park event is another group). I have a second board that is Registration and has people’s registration information organzied by groups, where the groups are the events they are attending (e.g. Inwood Hill, Pelham Bay, etc.)

I want to connect the boards and mirror columns so that the total number of people that have registered for an event ont he Registration board is counted and displayed in a column on the Event board. (e.g. 45 if 45 people have registered on the Registration board. I’ve tried so many things, and can’t make this work. Is this even possible or do I need to reconstruct the boards?

1
5 replies