Ability to show connected records on Calendar

Tables can pull data from connected objects. Calendars should be able to do the same.

Only way I know to show multiple objects on one calendar is to create add/edit form submit rules for multiple objects to all create records on single connected object (master calendar).

NOTE: Form submit rules for calendar event forms and show/hide rules on calendar details would also be helpful..

Yes, form rules for the calendar event forms are crucial for my company.