dual power input

Looking to re-wire some warning lights on a truck. Looking for advice on how to wire a relay(s) with dual power inputs. For example strobe lights are off but when brake lights are applied we want the rear red strobes to flash as well. And when strobe lights are on we do not want to back feed the power to the strobe controller or over power the led's and kill them.. how would we go about wiring these?

Maybe just wire tap into the wire that feeds the brake lights and use it to trigger a 5 pin relay.  Not sure if the trigger wire would see voltage if you had a power source hooked up to a switch also feeding the strobes at the same connection as the power coming from the relay, so you could just use a diode on the wire from the relay to keep it from back feeding when you use the switch. 

That made sense to me, lol, I could be way off though?

When you say "strobe lights" on with brakes, do you mean to power the strobe controller and its LEDs? If so, an SPDT switch could be used. IE - the strobe controller goes to 30. 87A goes to the strobe power (switch etc). 87 goes to +V else switched brake +V (if it handles the strobe current). 85 to GND. 86 to the +V switched brake signal. Hence the strobe "normally" passes thru 30 & 87A. When the brakes are on, the relay energises hence switching the strobe controller to +V.