I found the following answer for a brake controller

The purpose of a brake light relay kit is to prevent your towed car's brake signal from overriding the turn signal that comes from your RV. When your towed vehicle is properly wired and connected to your RV, its indicator lights will illuminate as you engage the turn signals in your RV. However, if you have only a four-diode system in place, the turn signal will be overridden by your towed car's brake signal as soon as your supplemental braking system presses the towed car's brake pedal. As a result, drivers behind you know only that you're slowing down and not that you are turning.

Installing a brake light relay in your towed vehicle fixes this problem by ensuring that your car's brake signal does not override the RV's turn signal. Therefore, your towed car's lights will function in accordance with your RV at all times.

Normally Open

The diagram and steps shown below demonstrate the installation for normally open applications. Be sure to follow the instructions included with your relay kit for a more detailed process.

Standard Normally Open Installation for Roadmaster Brake-Lite Relay
Remove the blue wire from the kit. This wire is not needed for normally open applications.
Locate the brake-light-switch wire in your towed car.
Remove the brake light fuse.
Cut the brake light wire a few inches away from the "cold" side of the brake light switch.
Attach the relay to the wiring for the RV braking monitor. The diagram above shows where the green wire attaches the relay to either a Roadmaster Even Brake or BrakeMaster system.
Connect the black wire of the relay to the brake light wire near the brake light itself using the included blue butt connector.
Identify a fuse that is only powered when the ignition is in the "run" position and not when it is in the "tow" position. Pull the fuse. Insert the fuse into the slot closest to the fuse blades, then insert the fuse tap into the empty slot in the fuse panel.
Using the attached blue butt connector, connect the red wire from the brake relay to the wire from the fuse tap.
Ground the white wire to your towed vehicle's frame.
Secure the relay with the included wire ties.

My question is: Is the #11, white wire from the BCM the wire I need to use in this case.

Thank you. I had already figured that part out. The #11 wire from the BCM has 12V when the brake is depressed but I am not positive that is the wire I need to tie into. I like your suggestion of trying to call the manufacturer. Will try that today. Thank you.