How to correctly set the group-ID in the fix orient/fcc command for an alloy with four elements

Hi everyone.
Here is a bi-crystal system with four elements (fcc CoCrFeNi), and I want to simulate grain boundary migration using the fix orient/fcc command. However, the explanation of the group-ID of this command confuses me.

Syntax:

fix [ID] [grp] orient/bcc <file0.txt> <file1.txt>

The manual written by Wicaksono says: “[grp] Group of atoms to which the fix is applied. Use all only if there is 1 type of atoms. If there are more than 1 type of atoms, e.g. a binary alloy, one must first create an independent grp that encompasses atoms that constitute the crystal (solvent, not solute). The existing fix command in LAMMPS will not see this difference. The adapted fix orient/bcc has also been modified to now consider the possibility of having multiple type of atoms.”

My question: There is no clear solute or solvent for the CoCrFeNi HEA. So how should the [grp] be set?