If the author sends you an early sketch/draft of your cover, save it and upload it as an overlay. If it’s approved, it means that the cover will also be approved once the final art is done. This is especially useful for covers with suggestive poses / themes and horror covers 
If it gets rejected, it also means that the cover will also be rejected, so you have some time to tell the author to modify the artwork. Hope this helps!
If it gets rejected because episode suspects it’s a stolen artwork, you also have evidence.
