Visual studio warns about storing projects in directories that are not sub-folders of the solution:
The project that you are attempting to add to source control may cause other source control users to have difficulty opening this solution or getting newer versions of it. To avoid this problem, add the project from a location below the binding root of the other source controlled projects in the solution.
How do shared projects fit into this constraint? E.G. Given
$\BranchName\Project1Name\Project1.sln
$\BranchName\Project2Name\Project2.sln
Where can I put MyCompany.DataLayer.projwithout
breaking things?