Our products cannot ship to California due to California environmental regulations.

How do I allow customers with a billing address in a restricted state to place orders to be shipped to an unrestricted state?
Restriction applies to all products sold on this website so I do not need a solution that is product specific. The solution can apply to everything sold on the site.

We just came across a situation where a customer located in California attempted to order some products to ship to her daughter in Minnesota. When she filled in her billing address, California was not in the list of states in the pulldown menu. (she cheated the system by selecting another state and then explaining in the comments box.)

How can I configure ZC to show California (and all other US states) in the pulldown menu on the "Payment Information screen (checkout_payment.php) and on the "Change Billing Information" screen (checkout_payment_address.php) yet not have California in the pulldown menu for the "Delivery Information" (checkout_shipping.php)?

Currently in admin-> Locations/Taxes
our list of zones shows country: United States and a zone for each state except California.

Zencart 1.3.8a