BuddyPress.org

In the activity loop for individual members, I’d like to add an option for ascending or descending order. I can see how to change the order by adding a filter on bp_ajax_querystring and it appears that I can override members/single/activity.php which I think is where I would add the second drop down to pick ascending or descending. But I can’t figure out how to put these things together. Any help appreciated.