SQL Server Questions - General

Hi Guys,

I know enough about SQL Server to be dangerous ;)

I have a 2012 SQL Server (on a Windows 2012R2 VM - ESXi) that I setup in our environment and can deploy new instances as required, or remove them, without killing everything. The Current SQL box has 3 running instances for our Payroll, Accounting and Rostering Packages and all are running perfectly with their associated Front Ends.

We are now looking at deploying Sharepoint 2016 and a Forms Based Software package into our environment. So I guess my question is: I need to use SQL as the backend for both of these so can I add more instances to the existingSQL server or setup a new independent SQL server with the new instances?

We are a smaller environment with approx. 100 users at most. Just basic office stuff on the most. The Finance team uses the Payroll and Accounting software...