no bus to bus routing possible,
but you should be able to send groups to aux mixes to the main mix and matrix mixes
bus to bus routing will lead to incoherent summing with possible phase shifts
and additional delay compensation would lead to higher latency in the system
both is not wanted for normal operation
maybe A&H is considering a mode with not strictly summing rules and the possibility to use bus to bus routing for a future update
some dLive users would welcome this as well