Background: This summer I was the instructor for a course in which many of my students were in high school, and were enrolled in my course as part of a 'pre-college' program at my university. This was a regular course, in no way modified for the pre-college students, and there were undergraduates enrolled simultaneously in the course.
I agreed to write a letter of recommendation for a few of the pre-college students for their university applications. The students' high schools seem to have differing levels of involvement in their college applications. One of them said their school is managing their application, and that I should send my letter of recommendation to the school who will then put it in their applications. I'd prefer to keep my part of their application separate, since I'm not affiliated with their school and don't want to run the risk of my letter being edited.
Question: Should I refuse to submit a letter to their high school?