A6 and A7 data communication is not compatible with each other,
and I would definitely put those two generations with a own Raspberry Pi controller unit.
And I would also run A7 and A8 generation miners with a own Raspberry Pi controller unit per generation.
7 and 8 are not compat either. A 7 on an 8 controller or vice versa does nothing to the opposite, miner won't even start.