Hi HomerJ,
The siteadmin that is active for your installation is declared within the siteadmin.xml. You should find it under the xml tag: DbName.
This can be found at the deployed 20qcbin.war file (path should be like the following: C:ProgramDataHPALMapplication20qcbin.warWEB-INF, this is the default installation path location and if you have a custom path specified during installation then you should adjust accordingly).

This should get you the active siteadmin_db from your installation. To verify that you have the correct schema, you can create a new blank project with a unique name and then go into that schema on your DB and verify that the Projects Table within the siteadmin_db you suspect has the new project as this will insure that you are then correctly pointed to the siteadmin_db schema you were trying to find (you can also just do this as a standalone to see the correct one for sure without going into the path structure).

Hope this helps,
Dan