Is it possible to create a SIS file that will:

1) Make a partial update (PU attribute) if the previous version of the application is already installed.
2) Will not fail to install if previous version was not installed.

Basically what I need to do is preserve one configuration file during update but also be able to make a clean installation. All with one SIS file.

PU attribute in PKG file works great for that, but fails to install if there is no previous version of the application.

Does anyone think it's doable?

best regards,