Getting actors to fall when they aren't connected to the group?

I’m trying to make a bubble pop game demo and I’m having trouble trying to figure out how I would get floating actors or a group of floating actors to fall down if they are not connected to the main group. Also I’m not sure how I would connect the actors as well. How should I get the actors to fall according to the picture example?

226736-bubbleexample.jpg

Hey there see if this helps. It’s in html5 and javascript but it might help you organize the code to do what you want.