Hi @lnewman1 
How to behave appropriately online is a surprisingly common challenge for teachers. I feel for you.
It is a 'teachable moment' but sometimes it's necessary to exclude so you can get things done.
You could assign your discussion to everyone in your class, other than the few who are not capable of acting appropriately online - yet.
By default, Canvas will set your assignment for everyone in your course. To create the assignment for a specific student/s, click the Everyone remove icon, then start to type in the name of a student. Search fields are dynamic, and you can search for students by first or last name. When the full name appears, click the name. Lists are not scrollable.
You can include more than one student in the To field as long as the students are to be assigned the same due and availability dates.
These few guides might help, especially the second one.
- How do I assign a graded discussion to everyone in a course?
- How do I assign a graded discussion to an individual student?
- How do I assign a graded discussion to a course group?
- How do I assign a graded discussion to a course section?
Sing out if you need a hand.
