Welcome to the Lab/Horn place...
The Lab12 driver is 6 Ohm (nominal)
Four 6 Ohm drivers in parallel result to 1.5 Ohm.
I think your 'all parallel' wiring will overload the amp.
You should connect each two drivers (of one cab) in
series.
From the Speakon's (1+) to #1 driver's (+),
from # 1 driver's (–) to #2 driver's (+)
and from #2 driver's (–) to the Speakon's (1-).
The two Speakons should be paralleled like before.
This will bring the impedance of a single cab to 12 Ohms
and when paralleled with a second cab will result to 6 Ohms per (amp.) channel.
I would also recommend installing double Speakon plates on all four Labs.
This will take one thing off your mind when setting up your system…