Keep Following path on duplicated layer

Hey guys ! 

I'm creating some lightning cartoon effect for a video. To do so, I'm using à simple path with some effect (wave warp, roughed edges, glow etc.) and an other path that automatically follow the first one (with à little gap to make a trail).

This creates me one lightning path and when I want to create more I need to duplicate both path. But when I'm doing so, the second path is not connected anymore with the first path. Or more exactly, it is still connected with the first path but not the one I obtained from the duplication. That is logic because the expression is just duplicated. But I'm losing à lot of time to relink it to the new one. Any solution ? Like, can I had something in the expression so when I duplicate it, it will be automatically linked to the new path ?

Thanks guys !