Wiring for Fake Horn Operated Ignition Kill Switch

I'm considering installing a fake ignition kill switch in my wife's car that when activated, it supplies uninterrupted power to the horn, and the only way to stop the horn from constantly blowing would be to disconnect the battery. I've learned that this could be possible using a latching relay. I want to do this to slow down any potential car thieves. In my car, the power for the horn first goes through a 15 amp fuse, then through the horn relay to the horn switch (the brake light switch and cruise control switch are both wired in parallel with this circuit). My only concern is, would the horn, the brake light switch, and cruise control still function as normal if it's wired this way? Thanks in advance