Just setup two calling groups. For those who will cover to the Merlin Messaging, put them in a cover group assigned to the calling group for the Merlin Messaging. For those who will cover to the Octel, put them in a cover group assigned to the Octel calling group. As far as setting up the calling group for the Octel 250, Octel provides the best job aids you will find for integrating to just about any system. Look at Avaya's site for the job aids.