You can access the new connection you created when trying to add an object or page to the PowerPoint template. When doing this, there will be a drop-down in the upper-right corner that allows you to select the connection.
The area that you are looking in is inaccessible to change connections.
Also, NPrinting 15 is no longer support so I suggest upgrading to version 16 at a minimum.
I was able to access the objects, but I kept getting an error that I figured was related to the fact that my connection/source wasn't done properly. I cannot see the objects I added on my PowerPoint template. I drag them over and nothing happens and then when I try to save and close, I receive an error.
Error HRESULT E_FAIL has been returned from a call to a COM component.
I cannot upgrade the version I am using or else I definitely would!