Pack 2 polymers in a cell with graphene sheets in it

Hello all, 
I have created a 5-layer graphene sheets and then rebuild the crystal to add additional space in C direction.
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Now, I want to pack the empty space with two kinds of polymer and do some additional step on it. I used Amorphous cell and packing mode to do this, but every time the job is failed. I tried to use iso-surface to solve the problem but the problem didn't fix. 
what should I do? 
Generally, is there any way to fill a cell with two kinds of polymer, while one or some graphene sheets exist in the bottom or both top and bottom of the cell??

Thank you,
Bests
Karan