You'll need to explain what you have in mind in more detail. I can follow that you want to make some "preferences" type settings for Company and Country, but I can only guess vaguely as to how those selections would affect the function of the rest of your database.
It's a solution cropping in other posts with the following relationships:
Patient < Calc < Prescription < Druglist > Drugs
So I'd like to have a 'Config' layout through which I could set what Drugs appear in the DrugList pop-up choices.
That still leaves out a number of details that could be critical to the correct function of your value list, but you can define a global field in the layout's table that links to an occurrence of the druglist table. You can then enter or select a value in this global field and a conditional value list can list values from this occurrence of the druglist table filtered to only list those that match the value specified in the global field.
Is that what you had in mind?
I may be wrong, but I don't think so because wouldn't a global field only permit a single 'top-level' value. What I was hoping to do was to have 3 portals, 1 for each of the fields: Company, Country, Product. So in portal 1 I might choose company A and E. I'd want portal 2 to list the 'countries' these companies market in, eg. USA, UK. Portal 3 would then list the products available in these countries for companies A and B. Individual products could then be checked/unchecked. 'Checked' products would the appear in the products pop-up (in DrugList in this case).
First you describe this in terms of value lists and now you refer to portals. While some methods can be used for both, others, such as a portal filter cannot. This is why I have been asking for a more detailed description of what you are trying to set up. And a match field can store more than one value separated by returns so there is not the limitation you may have imagined here.
So in portal 1 I might choose company A and E.
If the number of companies in your list are fairly small, a single global field formatted with check boxes might serve. With a larger number, a portal listing all companies with a button in the portal row that adds or removes the ID for that company from a (possibly global) field can produce the same result, but by using a portal, you can better manage a longer list of values by the fact that you can now use the portal's scroll bar to scroll through mutliple options.
The field populated with a list of values would then serve as the match field for the portal or value list for selecting countries (portal 2) and then Portal or value list 3 can list the products marketed by the selected companies in the selected countries.
But note that you need a data model to support this with tables and relationships and data in place to make it work.