I found that the fill lights can be used for directing interior lights in your models to do a variety of jobs. the problem is that they usually add monstrous amounts of time to the render. I'm still playing with them to find a happy setup I can live with. I learned that to keep the time down, light intensity should remain under 10 for these types of lights, and the number of points should be low also.

As my processor is only 4 gigabytes of RAM, I am at this time unable to work with more than four or five lights in my scenes with the main light being the default sun. Of course if I decide to add a sun to the scene along with the default one, I must make the default one my primary, and the secondary one must have less intensity; which I only make a visible light if it is within view in the scene. A third sun makes things even more complicated. Shadowing for such setups is the main reason I do this, as I make each sun a different color. this makes the shadows have colored effects, but be warned! Render times for such setups will be days if not weeks, unless you have a lot of processing power. Also In such cases, shadow softness needs to be low for all lights (suns), so that the intersections of the shadows will be a little more crisp.

I invite everyone to play with these suggestions and see what they can do with them. In a future posting I will upload a scene using this setup to dramatic effect. At this time it is not yet completed, as there are a couple of models I am working on in other applications that I plan to import into Bryce for the final render. Since the scene will probably take a lot of time to render, I will be making it no larger than 1600 x 900 px, Probably a good bit smaller.