I have a solution on which I have (more than) 2 projects.
The first project has a project reference to the second project. The second projec
instead of using projects as references use the builded DLL of that project for referencing.. if you do the same in every modules of solution u can solve it. if u have two projects named as 'main' and 'sub' then in the main project add DLL of Sub project as refrence file and the same time in Sub project add the DLL of main project as reference..