Hi Hakari
When you have enabled selection in your data grid 2, you are able to pass the selected list of objects to a microflow. You simply put a button which triggers a microflow in the action buttons compartment of data grid 2:
Within the microflow, you must have a 'list of (in my case Client)' parameter: this means that you pass on the objects that you have selected. Then you can freely use them to compare within your microflow (you will most likely need a loop for this)!
Good luck!