It is not clear in the Phabricator interface or in documentation how I can assign a parent-task to an existing task. In trac I simply add a "parent" ticket number, and the task automatically becomes a sub-task of the new parent.
How do I accomplish the same thing in Phabricator so that an existing task becomes the child of another task.
I accomplish this by going to the parent task and then "Edit Blocking Tasks."