However, if you want to have one solution that holds all the projects- there is no problem to do that.
As of the changes in the refrence, what you can do is the following- instead of referncing to the a dll that is located for version XX in one place, and for version YY in another place, do the following:
1) Subst the directory that contains the dll in version XX to some drive latter (e.g. r.
2) Refernce the dll that is located in the subst drive. (e.g. r.
Whenever you need to change your version to YY, all you need to do is to subst the directory of YY as your drive, and the projects will refrence the right dll.