eman wrote: “He [R’ Yaakov Kamenetsky} then stated that an essential part of the Kedusha of a Bas Yisroel is that her father knows where she is until he brings her to the chupa. I heard this 30 years ago, and I have not been given a satisfactory answer to how sending a girl to EY fits with what Rav Yaakov said.”
I think the fathers listening to Reb Yaakov’s hadrocha are sending to seminaries like Hadar where they keep track of the girls 24/7. The father has a shliach.