To define a hierarchical fairshare policy, configure the top-level share assignment in lsb.queues or lsb.hosts, as usual. Then, for any group of users affected by the fairshare policy, configure a share tree in the UserGroup section of lsb.users. This specifies how shares assigned to the group, collectively, are distributed among the individual users or subgroups.
If shares are assigned to members of any group individually, using @, there can be no further hierarchical fairshare within that group. The shares are assigned recursively to all members of all subgroups, regardless of further share distributions defined in lsb.users. The group members and members of all subgroups compete for resources according to FCFS policy.
You can choose to define a hierarchical share tree for some groups but not others. If you do not define a share tree for any group or subgroup, members compete for resources according to FCFS policy.