No, unfortunately this isn't possible.
The firmware grade of a Casambi unit needs to be the same as the network grade.
If you have a network with different grade than the Casambi unit has, you'll be prompted to update the firmware of the unit in order to add it to the network.
NOTE: Only devices which display as Classic or Evolution within the NEARBY DEVICES list can be updated to Evolution and used within an Evolution network. For specific Casambi products which can be updated to 'Evolution' firmware grade here: http://support.casambi.com/support/solutions/articles/12000058791-which-casambi-products-can-be-updated-to-evolution-firmware-