I have read spoilers for Cursed Child Parts 1 & 2 online...
Basically spoilers coming from the Part 1 preview. And it sounds like really bad fanfiction. It sounds quite horrifyingly bad if its true.
Edit: I have now read the spoilers from part 2 and if this is all true, it sounds like Rowling lost her mind by approving this. Apparently, Bellatrix and Voldemort had a child that was born before DH which makes no sense canonically and it just absolutely horrifying storytelling.