Isotope multiple filter in multiple box

Hi, i need to improve a very simple and rapid function in isotope. This is what i'm having: a sidebar with multiple selection boxes grouped by category something like this: Cat 1 (tag1, tag2,tag3,tag4),Cat 2 (tag12, tag22,tag32,tag42) .... In this moment the filtering sistem allows us to select only one "tag" per category. We need to have a class named "combo" where to let the user to select more than one tag and find the products with all that tags. Something like in this example: [login to view URL] . REMEMBER: If it hasn't the class combo we will select only one per time and groups will be used to filter together. We need a reset button for each group where to flush that group on the filter and to remove the selected item by clicking again on it.