[Closed] illumination

A question for the sparkies.

I have three outside wall lights all on the same switch. All nicely wired in so no wires visible.

I assume the wiring is chased into the wall inside and then goes out but not sure.

Question is can I get a PIR standalone or maybe even replace one with a PIR light and then make them all trigger off that PIR?

I expect the answer is probably it depends, but what are the chances of the necessary wires being at one of the lights; I* don't want to have to do any new chasing.
I assume they must all be joined together somewhere..

*not me personally