It sounds like you are not using the "Advanced Simulation Module" extension of SMRT software that includes optimizer/search routines.
You can ask the software to search for the combination of three products that maximizes revenues based on the sum of the three. There must be competition also involved in the market simulation. So, you need to be able to specify competitors...or at least a "None" (constant) alternative.
For more information, please read: https://www.sawtoothsoftware.com/download/techpap/asmtech.pdf