I created a workflow to add a new item in a discussion list. What I am
trying to do is to use discussion list for each task, and all replies
are different action items and comments. All of them are grouped
together and user does no have to enter the task name in each reply.

However, the workflow only adds each task item as Message content
type, not DIscussion Type. No matter how I change content type or
workflow, I still can not ask Workflow to create a Discussion type.

If the new task item is created as a Message type, then each reply
becomes a new message, can not group together due to hidden system
column is blank and workflow can not update it.

Any suggestions?