AppDomain Isolation Problem

I archived the back-end in such a way that the business logic is placed in dlls loaded at runtime. Using ShadowCopyFiles = true and file system monitoring, I can change the business logic without restarting the host process.

So far so good ...

Let us call hostdomaindomain A and one of the children of B.

Unfortunately, if I make changes to the assembly C referenced by B, but not to A, these changes are not reflected when B reboots. I assume that this is because A loads C. What steps should I take to prevent loading C?

This is the code used by A to load B:

        AppDomainSetup appDomainSetup = new AppDomainSetup();
        appDomainSetup.CachePath = ServiceDLLPath + @"\Shadow";
        appDomainSetup.ShadowCopyFiles = "true";

        ad = AppDomain.CreateDomain(assemblyName, null, appDomainSetup);
        ad.InitializeLifetimeService();
        try
        {
            service = (IService)ad.CreateInstanceFromAndUnwrap(assemblyName, 
                                  "AppName.Services." + typeName);
            service.Start();
        }
        catch (Exception e)
        {
            LogManager.Log("AppDomain load failed: " + e.Message);
            return false;
        }