I've set up 4 conditional value lists to narrow down the options for data-entry. Each list's items are related to all the selections before them, in order:
Product Category >> Manufacturer >> Price Group >> Description
I've used the recommended method of establishing a table relationship for each new field, then basing the value list on that relationship. The system works well for most products, but some product categories don't have a manufacturer or a price group. When that happens, there are no related records displayed.
For example I have a product category Administration Costs for which there are no Manufacturers or Price Groups, but only Descriptions. If I select that product category, then the product descriptions aren't available, because the table relationship requires that all three preceding fields be a match. I'm assuming that when a field is empty, there is no relationship inferred.
What I'd like is for the relationships to be maintained even when there are empty fields. There is another way to do it, but it's a bit of a hack solution that I'd rather avoid.