Small correction: with DT168 and DT164-W, multiple A&H consoles can have control of the preamps at the same time, and the audio can be sent direct from the DT boxes to both mixers. In this configuration, there is no single ‘owner’ of the preamps.
Søren is correct that Dante devices can be networked. There are some limitations on number of DT boxes and Dante cards in a system (especially when running Dante Domain Manager), documented in the Dante firmware release notes, but your setup sounds absolutely fine.