At my kids’ school, I know a lot of legacy kids apply ONLY to the legacy school. To me, that is like applying ED to college and benefits the boarding school like the ED option does. It insures that the kid they accept will attend thereby helping the admissions office manage yield and avoid under or over enrolling. I’m sure its a big part of of why legacy admissions rates are so high and why the yield rates at the top tier boarding schools fall into the 75-80% range which is huge.