How to identified a sub-grid

I'm working with crm 2016, I have a form with two sub-grids with views from the same Entity. When I click on the add one button of sub grid A I use certain business logic  when I use the add one  button of sub grid B I use another business logic. I need to know which sub-grid in focus or which tab in focus to distinguished between both.
How do I do that ? or if there is another option to do that ?