There are few options when one wants to create an 'Evolution' network:
1. Update the units individually to 'Evolution' firmware grade when they are unpaired, and then create a new 'Evolution' network.
2. Pair all of the units to a 'Classic' network at first. Then select "Upgrade to evolution.." from under 'Network' setup. This option will automatically upgrade all of the 'Classic' firmware grade units found in the network to 'Evolution'.
For instructions, please see the solution found in the link below: