From the knowledge base article on Dual Mix Rack Mode: “This connection is between Port-B of the Master to Port-A of the Slave, any format of iLive interface option can be used (currently EtherSound, MADI, or ACE) but if the Slave MixRack is one of the fixed-format types iDR-16, iDR-32, iDR-48, or iDR-64, then the link has to be ACE as port-A is fixed ACE in these units.”
https://support.allen-heath.com/hc/en-gb/articles/4404724708369-iLive-Understanding-Dual-Rack-mode
It sounds like you can only use the Dante cards for your dual mixrack connection if you switch the iDR48 to be the master and use the iDR10 as the slave with the Dante Card in Port A (and the other Dante card in Port B of the iDR48).
Good luck!
