A question on parenting

There are cases like post #2648367 and its children: several variations, and each of them has an older and newer version (Pixiv/Twitter, revisions, or something else).
Possible ways to organize them are a parent with two children, one of which also has a child (like the example above currently is), or just a parent with three children. Which way is preferred?

I believe this was elaborated in help:post relationships but it should be sort of like a stepladder.

You have your most recent revisions at the top as the parents, with the inferior versions (twitter, old pixiv versions) childed to those parents. Top revisions can then be parented to each other.

post #2533542 is a pretty good example of this.

For the specific example linked which has a series of images as the parents, IMO a pool would be the most appropriate. The parents would go in the pool, and the duplicates would be children of those parents.