possible answer to <R12> B

The question was about using a Y-cable…

Plug the 3-wire Y-cable into any port 2-9 (ports 1 and 10 have built-in motor controllers, thus they only take a 2-wire motor cable). Attach a motor controller to each connector of the y-cable (each motor needs it’s own motor controller) and attach the motors to the motor controller. The motors will now run together as directed by the program.

Specifically they OP misunderstood the rule. You can’t y off of a motor controller but you can motor controller off of a y cable.