Make Secondary belongs the jeff and marion users on sysusers group.

usermod -G sysusers jeff

usermod -G sysuser marion

Verify by reading /etc/group file

Note:

Using usermod command we can make user belongs to different group. There are two types of group one primary and another is secondary. Primary group can be only one but user can belong to more than one group as secondary.

usermod -g groupname username - To change the primary group of the user. usermod -G groupname username - To make user belongs to secondary group.