I had picked up a few pre-fabs of 1/4 sphere radiosity light sets( I think it was here in free stuff). They are grouped, in order to change them(which I almost always do) you need to un-group them in order to change their settings as a group. However if you do not re-group them and you select something else in your scene, you now have from 0-? single free floating radiosty lights. At this point you can CTRL-Z(undo) and step back to when they were grouped.(hoping you haven't overdone the undos). It takes a bit of getting used to, but there are tricks like setting them up off to the side and removing a few by CTRL-selecting in the group, or choosing different settings & colors. What I havent tried yet is: starting at the top and reducing or inreasing their intensity or color. There are so many combinations to try yet only so many days. :) Hope this helps