Make tasks dependent on successor, not predecessor? (base schedule on launch date)

Hi, 

I'm setting up a schedule in which everything depends on the launch date and is calculated backwards from it, e.g. "product pictures are needed 8 weeks before launch", "product texts are needed 2 weeks before launch etc".

So in case the launch date itself is changed (let's say postponed by a month), I'd like all tasks to automatically also move one month on.

So is it somehow possible to make tasks dependent on a successor, or one certain task that is after them? Or if not, is that a function that can get introduced?

Unfortunately our launch dates are changing a lot, so it's a real struggle having to manually move everything each time otherwise. 

Thanks!
/ Clarissa