Settings

Connections

Google Calendar and Google Tasks, the only two. Each person connects their own, and none is required.

What each one does

Google Calendar, two-way
Your events and deadlines appear there. A move in your calendar shows under "Changed since Sunday", or becomes one card if it passes a protected deadline. A payment date moved there never changes the payment, because the paper sets it.
Google Tasks, one way
Your task reminders go there. Ticking one there changes nothing here.