Originally Posted by Buzzkill247

sounds like you need a bosch DPDT relay 5 post. wiring the relay to run current constant on one post, but if the other engages click over and use that source of power. Might even want a secondary blinker relay to allow slow response of power switch, otherwise you will click from lit because parking, directly to lit because blink and back = end result, no blink

Disclaimer: enjoying vodka cranberry and i *think* i read that right - open to "that's not how that works challenge" lol I'm just a smart "idea guy" smarter than me people make it actually work

edit: might be able to reverse switch expectation on NO/NC and use a ground flip, so when parking line has constantly lit, blinker signal will cause an "outage" of power - this will mean the side lamp will blink alternate your front and tail turn lamp, but should work. and yes, switch to LED WILL require a resistor in-line for the power lines. so your parking lamp power would have to be tuned down to LED capacity. however above notion i suggested would simply "turn off" power to lamp, so no resistor need on that side