COUNTY MISSING IN LOCATION SETTINGS

COUNTY MISSING IN LOCATION SETTINGS
Hello, in the UK we have an official county called "Bristol, City of" or just Bristol. This is missing under: Store Settings | Location Settings | Base State. This seems to be the same list as used for counties when placing orders and will be a problem for our mostly local customers.

How can we add in this entry? How can we ensure that it's kept when upgrading?

Counties in the UK are problematic and often not helpful in addressing. It would be a preferable option to make the field optional when placing an order.