Time travelling adventure

What will happen if the Marauders (except Peter Pettigrew ) found a shiny golden necklace which apparently was a time turner and got sent 39 years into the future with lily and Alice .What will happen when they discover that some of them have children and even grandkids, the reason of their death and many more. How will Harry and Neville react to see their parents for the first time.

But what's a story without a little twist.

For the time travelers to return back into their timeline their is quite a complicated condition which could only be helped by the one and only James Sirius Potter and his long time crush.

What is that condition, why does it concern James Sirius and who the bloody hell is his long time crush, will the time travelers return to their respective timeline or will they be stuck in the future and what will be the adventure James Sirius and his crush will experience with the time travelers??

'Ohhhh god its really gonna be a long year and its all because of that handsome no I mean annoying git and his even so more annoying friends' thought Lily

Note- I do not own any characters they belong to the famous book author J.K. Rowling except for a few and I do own the ploy.