Excel 2013 How can I separate instances on the taskbar?

Hi, does anyone know how I can know which excel on my taskbar that are connected to the same instance?

Lets say I open two different instances of Excel 2013 (holding alt + opening a new instance/session of excel that runs separately).
Then I open for instance three workbooks in each instance/session. I will then have six windows open.

Is there a way to easily know which windows that are connected to the same instance? This is very important to me because I use macro-workbooks, and then sometimes I need to have them opened in same session, and sometimes I dont.. This is because they will either start automatic calculation, or they wont calculate at all.

I have the option "never combine" on the taskbar. And it didnt help to set it to "combine". Then all the six windows are combined to only one Excel-icon on the taskbar.

hope for help!!!

I have seen other post this problem on the web, but no apparent s0lution.

In office 2010 every session was in its own "window", (MDI) Multiple Document Interface. Now in Office 2013, it is SDI (Single Document Interface) is causing trouble keeping stuff separated. Is great for having multiple screens, but hard knowing which files are connected in the same instance...
Anyone else having this issue??