When you use Attendant Vectoring as mentioned above here are a few hints.
Queue to Attendant - Does NOT queue a call, but does sent the call to a specific attendant. (Complained to AVAYA about this and they said - 'working as designed'
Queue to Attendant Group - Queues calls, but how do you define a group? See change Tenant to pick a group for a specific tenant.
Some of this I mention just because I feel your pain.
To queue calls, use Queue to Attendant. Train the attendants on the use of 'Position Busy' buttons. I haven't found a way to ring two attendants with the same call. AVAYA uses a load balance calculation to distribute calls to the attendants in a group. Kind of like ACD.
Thanks...