As per this thread: http://social.msdn.microsoft.com/forums/en-US/csharpide/thread/f33c32df-14e4-4636-8c8e-c96f66666cb5/
"I can modify a C# project using notepad to make a file DependentUpon another file, but is there a way to do this in the IDE?"
All the links in the thread are dead. Anyone know something similar that can be used?