You can share entire calendars with all family members, it syncs instantly on all devices. You'll need Revolutionary or Legend for this, and support needs to activate the family option. Do contact us via the question mark to the right of your mailbox once you've subscribed!
This is old, but it shows how you can share the entire calendar and how it then shows up in the other account instantly: https://www.youtube.com/watch?v=n8l_xV6z8EY