I dont know of a master entity or controller that does what you are asking for. What I do is for each light source, I usually do a second generic light with the following properties:
color: must exactly match the color of the light it is "helping"
50% falloff: X, where X is the distance in units from this light to the farther side of the room it is illuminating
100% falloff: 2X (or, double the distance)
Here is an example. Try this out in a long generic room with some static props laying around for testing purposes. where you have a blue-white spotlight pointing directly at a wall. the spotlight will naturally illuminate some of the area around it, and not just the wall. however, to simulate radiosity and "micro-light" reflections, use the second "helper" light, a generic light. Put it halfway between the spotlight and the wall, and give it the properties i mentioned. If you have done it right, you should be able to walk down to the farthest end of the hallway or room you made and still see the wall and some of the details - and shadows - of the static props you might have placed in that room. you may have to improve the quality of the lightmap shadows in order for this to really work, so experiment.
finally, sometimes pitch blackness is a good thing so don't try to totally obliterate the blackness. doing it the way i described can be more time-consuming, so think about that when mapping.
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