Fixing the position of multisphere particles in the simulation domain

Hi,
I need to fix the position of some multisphere particles at a specific position in the simulation domain before starting a CFD-DEM simulation. I am having a hard time finding the right command or approach to do this. Is there any way to fix the position of each multisphere particle in the simulation?
Something like the "set" command for single particles in the "twoSphereGlowinskiMPI" tutorial files:
...
atom_type granular
....
# create single partciles
create_atoms 1 single 1.2 0.5 0.5 units box
set atom 1 diameter 0.18 density 1.5 x 1.2 y 0.5 z 0.5

I want to do something like this (fixing position) but for multisphere particles. I would appreciate it if anyone could help me.
Regards, Hamed.