Hello @Kerwin,
I am the applications Engineer for the AD1937. This codec does not tri-state the unused slots in a TDM stream so you cannot share the same TDM data line. The clocks can be shared as long as there is enough drive strength and the signal integrity is taken care of. The AD1937 can be run in Daisy-Chain mode to add more data onto the TDM stream but not in stand-alone mode. I am fairly certain that this eval board is running the CODEC in stand-alone mode.
Thanks,
Dave T