I don't know if this helps you or not, but I've implemented multiple calendars by utilizing the tags feature. For example, certain people in the organization such as the pool manager, social chairman, etc. have admin privileges to add/edit events. When the pool manager adds an event, he adds the 'pool' tag to the event. When the social chairman adds an event, she adds the 'social' tag to the event. Sometimes there is overlap (e.g., community Luau at the pool) where the event would get both the 'pool' and 'social' tags. See http://help.wildapricot.com/display/DOC/Event+categories+(tags%2C+labels for details.
Then I create several calendar pages (this is the functional Event Calendar, not the template). Then I edit the settings for each calendar page and under the "events to show" category, I choose "Show events of these categories only" and check the 'pool' checkbox for the Pool calendar, the 'social' box for the Social calendar, and so on. See http://help.wildapricot.com/display/DOC/Publishing+your+event+calendar for details.
Like I said, I don't know if this solves your problem or not, but it has worked for us.
Kim