Hello,
If you understand correctly, you want to create big clumps based on the guides. Then create smaller, random clumps based on the big clumps, right? We call this "sub-clumping". For that you need to enable the clump index channel generation in the big clumps and then use that channel as a region map in the smaller clumps.
Demo:
Sample scene: https://www.dropbox.com/s/x490ary8bu1nkjp/SubClumpingSample.mb?dl=0
Documentation describing the steps:
https://ephere.com/plugins/autodesk/maya/ornatrix/docs/3/Clumping.html
Jeordanis Figuereo (Product Designer. EPHERE Inc.)