[Semediawiki-user] Is it possible to use a pre-loaded field value in a "values from concept" line?

[trueskew <tru...@gm...>]

I've got a form that I'd like to re-use, preferably without breaking it into
a series of includable templates.  It has a drop-down box that lists
companies in specific countries.  When I add an employee, I'd like to list
only the companies that are in a specified location.
 
For example, I've got a "Template:Employee" location field, "Company
Location", and I can pre-load it in form "Form:Employee Form" using with 
 
    {{#forminput:Employee_Form|button text=Add Employee|query
string=Employee[Company Location]=United States}}
 
That part works fine.  Conceptually, I'd like to do this
 
    {{{field|Company|values from concept={{{field|Company Location}}}
List}}}
 
to effectively get this
 
    {{{field|Company|values from concept=United States List}}}
 
reducing the list box to just the United States companies (from
"Concept:United States List").  I know this doesn't work empirically (and if
it's a syntax error on my part, that would be great).  Is there some way to
achieve this?  I can try to do a better job of explaining if I'm being
unclear.
 
Thanks.
- skew