Hi Mr Bigman,
We only support multi-surface operation on the same MixRack via our own gigaACE or fibreACE cards. You can still use a Dante card in the Surface for recording and interfacing with other Dante equipment, but it sounds like you will need a gigaACE card in the CDM64 to make your system work. Alternatively you could consider investing in a second MixRack e.g. DM0 which would also give you 128ch of independent processing / mix and more flexibility.
I see you’re based in Nigeria? If so you can reach out to James at PAXT (+44 1223 830 800) http://www.paxt.com for further advice.