I need a combobox to be bound to a field in a table. The field on any given record will contain one of three values: blank, a value which is in the combobox's rowsource, or a value which is not in the combobox's rowsource.

I want the combobox to display the field value to the user in all cases.

I also want the combobox to accept the same three different values from the user and save them in the field (ie. blank, non-rowsource value, rowsource value)

The rowsource may contain a large number of values which have to be retrieved from a database situated across the network,and I don't want to load the rowsource unless the user actually decides to change a value (or clicks on the dropdown).

Can someone tell me the best way to achieve this?