Attach to running excel workbook Application Modeler

Excel 2016, 64bit application.

I've created some menu navigation steps in Object Studio, Everything works if I have excel launch as a new application from within the modeler....
When trying to attach to an existing workbook within the modeler, no combination of things seems to let this happen successfully. I end up with errors that say a connection could not be made.

If I have a workbook named Book1.xlsx, running and visible.... with no other workbooks open.... what settings would you use to attach to it from the modeler??? It has to be in the modeler because I am using UIAutomation to navigate the toolbars.

Also, as a followup, my next question is how do I pass a workbook name from a process into an object to make that connection more dynamic and not yet another hard coded problem.
I found out how to pass handles between pages and stuff. This is done by right clicking on the "start" item on the object and setting inputs required there.

Still zero solutions for attaching to an existing excel instance using the Application Modeller though.