How to do major upgrade conditionally in installshield

Question

Here's my scenario:

I need to have the ability to have different versions of the same product coexist on my machine. So, I need to have a different product key. Cool, no problem. The thing is, I also want to have the option to do a major upgrade ONLY if the user is trying to install to the same location that my product is already installed to.

So basically, I need to be able to launch the "major upgrade" mode AFTER the user selects the location they want to install to.

How might I do this?

Answer 1

I know of a way to do what you describe but I'm not sure it's what you want.

What you probably want is multiple instance installers. Take a look at the following article to see if it describes the experience you are looking for:

InstallShield 2009 Beta Part I ( Multiple Instances )