Grant KEN to manage group membership
Step 1: Active Directory Users and Computers
HOD distribution group is managed by Kaiming Liao

Step 2: Exchange Management Console connected as Kaiming Liao
Add Ken to the Managed By list:


New-ManagementRoleAssignment -Role MyDistributionGroupMembership -Policy "Managing Distribution Group Membership"
New-ManagementRoleAssignment -Role MyBaseOptions -Policy "Managing Distribution Group Membership"
New-ManagementRoleAssignment -Role MyContactInformation -Policy "Managing Distribution Group Membership"
New-ManagementRoleAssignment -Role MyTextMessaging -Policy "Managing Distribution Group Membership"
New-ManagementRoleAssignment -Role MyDistributionGroups -Policy "Managing Distribution Group Membership"
set-mailbox ken -RoleAssignmentPolicy "Managing Distribution Group Membership"
set-mailbox tom -RoleAssignmentPolicy "Managing Distribution Group Membership"