Please help me in my DIY mod effort on Deadpool Premium.

My goal is to improve the light show during Disco Multiball. If you don't know the game, it has a mirrored disco ball that turns during the mode. Two anemic spotlights - hidden on the nearby sculpts of Wolverine and Dazzler - throw light on the ball as it turns, creating the classic, disco-tech dance-floor effect. I want to use Comet's Matrix System spots to blast that disco ball with LOTS of light during the mode, to really get the scattered-light effect. I want the lights I add to (a) be synced to the electric motor that spins the ball, and (b) be powered by the 12V accessory power accessed via a connector in the backbox. I have no experience with relays, but I assume I will need a relay to open/close the circuit for the lights. The tricky part is, how do I tie the operation of the relay to the electric motor? The motor is powered by a nearby board. I don't have the schematic for the board. It has three connectors: one for power-out to the motor; one for power-in to the board; and one out to something I haven't yet traced. I attempted to show the board here, but it's tucked behind the wiring harness and is hard to see. Its markings suggest it's supplying 48VDC to the motor and to the as-yet-unknown other recipient. I should also mention that I spoke to Gregory at Comet about this but he had no suggestions.
Any ideas would be much appreciated.
Thank you for reading my post!
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Thanks, LTG, for your suggestions.
I know too little about relays to know if one could be actuated simply by tying it to the electric motor where the leads attach.
Is there such a thing as a photosensitive relay? That would be ideal.

Thanks, PSP! I asked for help, and you provided LOTS of help. Whoa! Still, as a layperson, this is mostly Greek to me. Clearly, I'm going to have to learn *many* new things to pull this off. Hopefully, I won't have to make a complete nuisance of myself - to you or to this forum. Naturally, I immediately searched for these parts, but I can't find stock of the BUK7240 anywhere. Can you suggest a source? I do see the optocoupler though from Mouser:

https://www.mouser.com/c/?q=859-LTV-358T&m=Lite-On&utm_source=octopart&utm_medium=aggregator&utm_campaign=859-LTV-358T&utm_content=Lite-On

As for the diode, I'm not finding a basic diode when searching "Schottky SK510." Again, can you suggest a source?

I will print off your schematics and do my level best to understand them. I discussed all this with LTG, and, while he's not entirely solid on what you're proposing, he does at least agree that it's much simpler than what he proposed earlier in the thread. I tend to lean on LTG a lot - for better or for worse! I think good first-steps for me are to (a) print off the schematic and figure out what I'm looking at, and (b) order the parts I will need. I have bulbs, sockets, Matrix System extension leads, misc. wire and heat-shrink tubing, and a soldering iron. I will need to make a harness with a connector that can plug into the accessory jack on the SPIKE2 power board in the head. That harness can supply 12V to the sockets/bulbs. If I'm mistaken and it actually supplies a different voltage, I will naturally need a transformer. It sounds like the power will go straight to the bulbs; only the ground will be controlled by the optocoupler. I will probably skip the inductor/EMI filter as I don't imagine I will notice a blink or two from the lights.

Hi, PSP.
Wow. Again, a wealth of information! I'm confused by how these same parts you suggested are actually already present in the game, hiding in plain sight on that controller board. Your diagram indicates it would be simple to connect a LED strip to optocoupler, but I don't dare solder anything to any part on that or any other board in the game for fear of damaging something. You must think I'm an ingrate, since you're presenting me with a clever/simple'ish solution and I'm not scrambling to try it. I apologize. What risks to the controller board do you foresee if I were to try the tie-in you're suggesting? What is the likely spot of the solder pad or pin on the optocoupler? Will it be obvious? Clearly, I would like to solder my lead from the LED strip light in the right place and not the wrong place.
Thanks for your patience. Sorry I didn't respond sooner.
J