First I want to thank upfront to anyone who will answer my question.
My problem is: I have created "base control" and from the base I have inherited my "main control". Now user will be adding my "main control" to the toolbox such that he (the user) can only drop it on the form on any project he wants, but I am getting error because the "base control" is not automatically referenced in the project where the "main control" is dropped. Only the "main control" automatically is referenced.
Just to mention that both controls are signed properly and will live in same directory when added in toolbox, but not in the GAC (It will really not work for me, unless there is no other solution).
I have found similar question here but it is not answered and unfortunately I can't find answer anywhere at all.