So according to the Parent and Child Posts Guidelines:
Choosing the Best Parent
The Parent post should be considered in this order:
Most Original, as opposed to confirmed derivatives.
Most Exploitable variation of the post for creating derivatives.
Most Complete, as opposed to cropped posts.
Highest Resolution.
Cleanest, containing the least watermarking.
The most original, unaltered and earliest version of a post should be considered the "parent" in a post relationship, not the revisioned and more recent version of that post, or at least when it comes to comic post.
Yet I don't understand why it is the other way around in reality.