When setting up subscription licences for a company we have found the best practise to be as shown below.
- Information about assigning licences can be found HERE
- Information about managing seats can be found HERE
If the TID is given ADMIN rights then when that TID is used to log into their licence manager there will be the option to switch accounts on the left hand side. This will show you the accounts that you have been made a delegate for and allow access the OWNER account to assign and unassign licences and add users.