We have a table of Suppliers.
We also have a table of Tasks.
When defining a Task, the user chooses a Supplier from a value list that is filtered by Territory. 

i.e. the Task will have a Territory defined and only the Suppliers operating in that Territory are selectable.

However there are some Suppliers that work across ALL territories.

I would like to have a way that these Suppliers are included in the value list for ANY territory, so if the Task has the Territory defined as (say) Sydney, the value list will show the Suppliers relevant to Sydney AND Suppliers that cover all territories.

Ideas?
 

Use a calculation field (defined in the Tasks table) =

List ( Territory ; "All" )

as the matchfield for the relationship, instead of the Territory field.

Perfect.

Thanks.