Custom build, additional dependencies

[OReubens]

Is there a way to tell the VS2010 compiler/make to use an entire project subfolder as an additional dependency in a custom build step ?

I'll explain.

Suppose I have a C++ Application project with with following Project Solution layout

Solution 'MyApp' (1 project)
   MyApp
      External Dependencies
      Header Files
         MyApp.h
         resource.h
         StdAfx.h
      Source Files
         MyApp.cpp
         MyDataParameters.bar
         StdAfx.cpp
      Resource Files
         MyApp.ico
         MyApp.rc2
      MyDataFiles Files
         MyData1.foo
         MyData2.foo
         MyData3.foo

I have a Custom Build Step defined on MyDataParameters.bar.

Is there a way that I can automagically tell VS2010 that it should add all the files in the 'MyDataFiles Files' folder as additional dependencies for that Custom Build Step?
This is a simplified example of course. I know I can do this manually by specifying
MyData1.foo;MyData2.foo;MyData3.foo
But I'm needing this for a couple hundred projects and the number of additional dependencies per project amounts to several dozen up to several hundred in some projects. Setting the dependencies manually is extremely annoying and error prone.
The list of files to be processed gets changed regularly which is why doing it manually is such an annoyance.