Car: 2019 Lexus IS350
Link for lights at bottom of page.
Link for piggyback at bottom of page.
Link for Fuse box diagram at bottom of page.

I am currently trying to figure out how to power my 10 puddle lights that will go under the car. But the things is I want to have two power source. One that turns on with the dome lights and one that turns on with the headlights. This is so that when I unlocked the car the LED lights turn on and the other is for when the headlamp turns on the LED lights turn on as well and I'm only running it from the fuse box (easier to make a cleaner look), I don't want to t-tap any wires. Both of them are 15A fuses(dome light and low-headlamp) but what I'm worried about is, can I piggyback both of the wires from the low-beam headlamp and also dome light, adding another 10A or 15A fuses between each piggyback, and join them together at the power side of the led light and be safe? I'd hate to send power to the headlamp when it not on and vice versa or blow a fuse or light. Negative will ground to anything that close.

(Lights)Amazon link : https://www.amazon.com/gp/product/B...DCNXW&linkId=c718d466641dff44e35133881fa5bd65

(Piggyback) Amazon link: https://www.amazon.com/Circuit-Adap...ocphy=9015399&hvtargid=pla-2281435178338&th=1

Fuse Box: https://www.startmycar.com/us/lexus/is-350/info/fusebox/2019

 

What happens when you connect power feeds is that when any one of the feeds is powered, they all are powered, meaning that EVERYTHING on each circuit gets powered. That is the good part of the reality.
The unfortunate part is that if there happens to a short circuit to the chassis ground negative on any of those wires in any of the circuits, current will be flowing thru all of the fuses, a lot more amps than the wires were intended to carry. THAT is the bad part. The results of a shorted circuit might be unfortunate.