Installshield Pro 5, 6 Update/Uninstall Question

I have a unique situation that I need help with. I have an application that was distributed using IS Pro 5. I am trying to install version 2 of this app using IS Pro 6. But, here is where things get tricky. I need to keep a separate instance of the old version around, so that when the new version is uninstalled, the old version becomes active. Also, the user should be able to uninstall all old version without affecting the currently running version. And, to complicate things more, the app runs as an NT Service.

I am able to handle the new versions fine (i.e., v.2, 3, 4, etc.) by storing all their required services, environment variables, etc. in their registry key to be restored when they become the active version. I also instruct them not to delete the services, etc. unless it is the last instance to be removed (i.e., there are none left, although it is tricky to know if version 1 is still around). But, since version 1 is already deployed, I am unable to change its uninstaller to handle these cases. As it stands now, uninstalling version 1 will delete the service and envirmonent variables needed for the currently running version. I need to prevent this if a new version has been installed and is still installed.

Is it possible to change the uninstaller for the previous version that was created in Pro 5 to check for these things? Can I just replace its uninstall with a new one created in Pro 6? If so, how is that done? I didn't write the Pro 5 install, and I am unfamiliar with Pro 5 semantics (which I know are quite different than Pro 6). Is there a better way to do this than what I am describing? I know IS Pro 7 discusses multiple instances running concurrently. Has anyone used this, and can you tell me how/if this would work for my situation?

Any input is greatly appreciated.

thebert99

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