Grouping Windows based on creator

Some applications have single PID with multi instanaces running Eg: Word or MS Teams

I need to automate UIA but hoe do i differentiate the windows created by a specific instance

Eg : on MS Teams I can have two Instances running under the same PID

Let us assume the instances are A and B

Now If I create a pop up From Instance A how do i associate the pop up to instance A and not to instance B ??

Given the window handle of the pop up I am unable to find the owner of the window that goes back to Either the window handle of A or B

One option is to hook onto the object create event and keep a list of all windows created but in case of MS Teams the second instance is launched from inside the first instance so it is both a second instance as well as a pop up/ sub window.