Upgrading Assistance please V9 to V12

Waves Plugins Questions:

If I have to uninstall V9 to upgrade to V12, will older Pro Tools projects put the V12 plugins in place where the V9 had resided? Will plugin parameter settings remain?
Can you explain why this works? IE Metadata remains identical/database is the same etc.

Or is is a re-do of all plugins for each project?

Waves Mercury Bundle with Studio Classics - legit
Pro Tools Native 11.3 Perpetual / Avid Analog 16/16 interface
Win 10 1909

Hi @endoverendstudios welcome to the Waves forum!

Note that newer versions will indeed load instead of older plug-ins, with the saved settings as before.

We also don’t change the sound of the plug-ins in updates.
First, because they sound good but mainly so that in-progress sessions will not be affected by this.

If there are any issues with updating or with loading older sessions, you can always feel free to contact our Tech Support team to assist according to your exact setup and licenses.