checkbox state per card

[Jamie]

I'm making a simple database.

It's cool that fields from a shared group can have different
contents per card automatically. This is very helpful.

Checkboxes from a shared group don't seem to have the same behavior.
Setting such a checkbox on one card changes it on all cards.

What is the simplest way to make a checkboxe remember a separate
state for each card?

Thanks,
 -Jamie