[BirdOPrey5]

If you look at your post table in the database you will see forumid of a post is not something that is stored, but threadid is and in the thread table the forumid of the thread is available.

That means in your custom script, whatever it is, when it selects the posts from the database the query must "join" the post and thread tables so that the forumid is available. If you can find or make this query then you can make sure forumid is something you can find from the $post array or whatever you are calling it.