Let me explain my view point.
In the picture that shows the loader valve fig 11, item 5, shows the loader valve with steel line to 3pt removed. That line went to the top of the transmission.
This port with elbow pointed to the rear is now the PB/pressure line to the IN port on the BH valve.
In fig 12, that port goes into tank and in used to connect the OUT port from the BH valve. 3pt is not used and should be plugged.
If you had T-N-T/remote, installed , you could bypass this valve.
If you had remotes and BH installed, the remote valve PB would feed the BH.
If you then had a 3pt BH, you would use the PB from the BH valve to feed the 3pt port on top of the transmission, and send the OUT port to the port in fig 12.
If you removed either BH, you have to re-establish the connection from the loader valve to the 3pt port.