Looks like all messages in a thread must be children of the first
message. I got phorum up and running along with Campsite and its quite
clear that this is how they intend it to work: for example, in the
Phorum interface, the first message in a thread only allows you to
delete the entire thread, and not the message itself. All the other
messages you can delete individually. If you post using Campsite so
that parent ID is zero, the message appears as a new thread when you
look at the index of messages, but when you read the thread it is in the
right place.
If we were to follow the phorum way, so that Campsite seemlessly works
with phorum, we have two solutions:
1) Create the first message of a thread automatically whenever you
enable comments for that Article. The message will be empty and the
subject of the message would be the title of the Article. This first
message cannot be deleted, but it will be "hidden" if comments are
disabled. The subject line of this first message must be updated
whenever the Article name is updated.
2) Dont create the first message, but whatever the first message is, it
cannot be deleted unless you delete the entire thread.
I think #1 will look nice and make more sense when looking at comments
in the Phorum interface.