[@johnjamesjacoby Keymaster 6 years, 10 months ago]

Hierarchical replies do not use the post_parent column. Replies always use post_parent for the topic ID.

The hierarchy/relationship is instead determined using a piece of postmeta, similar to the topic and forum connections.

So when you say they aren’t working, are they really not working visually, or are they not working the way you expected them to?

We coded them this way, so that all post to post relationships could use the same mechanism, eventually allowing them to be swapped out for something even more performant later (taxonomy connections, or a custom database table.)