Detect packages on the second installer run

Hello,

Please help with the following situation:

1. I run my installer with my packages and everything installs fine
2. I run the installer and I would like to detect, if possible, all packages that have been installed previously, and disable them from being selected

I know that I can find the registry path from the uninstall.xml file, from the first installation, but can step 2 be done?

Thank you in advance,
Cosmin