I have a forum "Relationships" and a topic "abc". What else do I need do to with the database to have topic "abc" listed under forum "Relationships", apart from the following?
Topic "abc" clearly shows that it's in forum "Relationships"
1.1. In WP backend view
1.2. On frontend
1.3. In database
However, forum "Relationships" shows 0 topics
2.1. On frontend
wp_postmeta table
Background info
The forum is created using WP backend.
The topic and its postmetas and the forum's postmetas are added by my PHP script.
(this is because I'm migrating data from 1 old WordPress site to a new one using my PHP script;
there are 2 WordPress databases here so I can't leverage on WordPress functions)