One way power splitter?

[unssafe]

Hey now,

I am going to install rgb led strips footwell lighting that I want to come on when the dome light comes on and also when I have the cup holder and door coin holder lights on. So i will need a splitter of sorts that won't let power go back to the other lights, a one way type of thing. I hope somebody can I D the part I am trying to think of and place that sells them.

Thanks in advance