Trying to filter based on selected checkboxes

I have an app that shows a table of different "Lots" within these "Lots" are different "Runs". Right now I have it so that you can select a Lot and see the Runs inside that Lot, kind of like a folder hierarchy.

What I want to do is select multiple Lots to see the Runs in multiple Lots. In my Lots table I have checkboxes for each row but not sure how to set up the functions in the model and controller to get runs from the selected lots. 

Any help you can give is much appreciated. Thanks