Question: Security System & Aux Battery

Good Day All.

I have a Daymak Gatto Scooter / E-Bike that I purchased used. 700km.
I like it. 750W, 48V. My only complaint is that the controller seems to lack a connection for the regen brake thumb switch.

But onto my question. It has a security system on it. 12V.
Only thing is it is directly powered from the controller, which is ultimately in series with a 12V 4-Pack 48V source. My battery wires are hard to conceal and one snip or disconnection and the security system gets bypassed and powered off.

I have a 12V battery from an old home security system. SLA.
Is there a simple safe way of wiring that battery into the alarm power circuit? Other than just tapping the line in parallel?

I was thinking that this could also be used for some other power ideas too. Like aux power for audio and custom lighting / utilities?