Hi AgentSmith-- Actually, you can't do this in Bryce. Source "D" in the material editor has always "stood alone" so to speak -- you can use it in any of the slots, but cannot be used in conjuction with the other channels. Bryce has always done "A", "A-B", and "A-B-C" blending, but has always excluded D as sort of an "extra" slot... -Brian