Grocery IQ: Sharing Between Devices?

Test driving this app for the first time.

I figured out how to share my list with another user. How do I share/sync between two of my own devices (iPad and iPhone)? Do I need a separate account on the second device to "share" with, or is there a way to sync?

Thanks.

There was no Email. I turned sharing on and entered the other person's Email address. That person got an in-app invitation. It didn't come up until I tapped on the "Settings" button. Not sure if that was by design, or just a coincidence of timing.