Additional materials for Dartmouth waitlist

I was waitlisted at Dartmouth and want to submit extra info to increase my chances of acceptance. I’m going to write my regional admissions officer restating my interest, but also…

what I am wondering is: I never submitted a Peer Recommendation, and am considering having my older sister write one. On the other side, I could have my English teacher write a letter instead. I’m not sure how much either would help more - a (late but very strong) peer recommendation vs. another strong teacher recommendation (which could be repetitive as I had already 2 teacher recs & a counselor recs).
Would it be better to submit the peer rec or another teacher rec?