getting all delegated admins

We have a group of admins that are also trusted to manage our customers through delegated administration.  How can I list all those admins? 

The closest I have come is:

Import-Module MSonline
$cred = Get-Credential 
Connect-MsolService -credential $cred
$delegatedadmins = Get-MsolRole -RoleName 'Service Support Administrator'
Get-MsolRoleMember -RoleObjectId $delegatedadmins.ObjectId

but I wonder is it is true that all Service Support Administrators ar delegated admins?