Boby:
I think that you should anticipate a solution to this multi-way PWM function through the use of a time-sliced state machine. If you do it correctly you can use almost the same concept that you used for the single channel solution. I suggest you study a posting I made a while back that demonstrates how a time sliced state machine works.

State Machine Tutorial

Then it should be relatively easy for you to adapt the concept you have to 5 or even 8 channels.

Michael Karas