You are able to co-teach with a colleague. I do this all of the time with my fellow teachers. One teacher becomes the teacher-of-record and creates a class with the name of the teacher you wish to co-teach with. I might, for example, create a class called Hicks / Grimm. We would forward the join code for that class to all of our shared students. The second teacher (or as many folks as you please) would join as a guest with the "join essay" code. See the screenshots below.
Now we're teaching all of our students together. They can be clustered and monitored in the Hive very easily, and commented on by any of the participating teachers. Give it a go, and keep in mind that you can invite other people into the essay as well, such as administrators, parents and older student mentors. Let me know if you have any other questions. Keep in mind that the original course creator is the only one who may modify the lesson itself, so the co-teacher would make a suggestion and the teacher-of-record would implement it.