Charge adjustment on clustered system

Dear LAMMPS users,

I am trying to calculate the free energy of silver nanoparticles (clustered) and adjust the total charge of the clusters based on the free energy calculated (by comparing free energy for different charges of the cluster using FEP package). But it seems fix adapt or fix adapt/fep command cannot be used in dynamic groups setup. I would like to seek suggestions on how to do charge adjustment on dynamic group setup or using chunk-ID of the clusters.
Any suggestions are welcome.

Thank you.