With 2 surfaces you will need 2 mixracks and link them via ACE or other option cards in their Port B slots to to a full 64ch monitor split. You could wait for the new Dante cards to put in the Port B slots (to do the split) and also gain 64 ch recording/playback capabilities direct to computer via Dante virtual soundcard - and then sell the 24 track ADAT.
There is probably other options using a smaller IDR32 mixrack and an IDR0,Ace cards, an XDR16 for additional I/O and fitted with an MMO card for recording? Perhaps A&H can recommend a suitable solution like that? Someone correct me if that’s not possible - not sure on the IDR0 capabilities with fixed format iLive’s!