Multiple Databases on 1 server

Okay, here is the sitution, we currently use SD+ for our IT Service Centre, and now want to use it for our Finance department.
Our company policy is to have app and db seperate, and I know we can only have 1 instance of the application on any server(unless this has changed)

I have 2 app servers, 1 for each instance, now I want to have the database on the 1 server though, is this possible? We have MSSQL database currently and want to do same for Finance.

I ask as when I go setup new instance of SD+ on second app server I need to specifiy database name, but in the "ataBase details panel" the option to change is set to Servicedesk and I am unable to change as it is greyed out.

Version 7021

Plaese assist if possible?

Thanks in advance