Thank you for the question.
Unfortunately, I am not able to answer questions directly related to manuscript submittals.
I would hate to give any possible mis-information that may casue point deductions.
I can only suggest that you follow the guidelines for the use of the dash. Then in the letter to the grader make sure you cite the reference and rationale used to make your decision.
If you have any further questions about specific issues on your manuscript, you can email Jennifer Dunnam at email@example.com.
She oversees the manuscript grading process and will often give guidance for difficult situations that arise on manuscript submittals.