There is no support for "Share" in TFS. You may be able to leverage two different TFS workspaces to accommodate your requirements, or you may be required to do some restructuring of your code.
(Historical note: "Sharing" actually came from Visual SourceSafe and SourceGear Vault added it because we wanted feature parity with Visual SourceSafe. Our goal at that time was to build "a compelling replacement to Visual SourceSafe", which meant we had to implement share and - much worse - pin.)