Responsa for Yevamot 213:9

נכנסה לחופה ולא נבעלה מאי איכא למימר לא ניחא ליה דתיהוי חופה דאיסורא מסר האב לשלוחי הבעל מאי איכא למימר לא פלוג רבנן ובית הלל כיון דאיכא קדושין וכתובה לא אתו למימר דבעילתו בעילת זנות

then, could be advanced where the father<span class="x" onmousemove="('comment',' V. Supra p. 739, n. 9. ');">²⁶</span> had entrusted her to the representatives of the husband?<span class="x" onmousemove="('comment',' Though such an act on the part of the minor's mother or brothers constitutes marriage in accordance with Rabbinic law, as does such an act on the part of the father even in the case of one who is of age (cf. Keth. 48b), nevertheless the question of fornication does not in such a case arise. Why, then, do Beth Shammai forbid mi'un even at this stage of marriage? ');">²⁷</span> — The Rabbis made no distinction.<span class="x" onmousemove="('comment',' Cf. supra p. 739, n. 11. ');">²⁸</span> And Beth Hillel?<span class="x" onmousemove="('comment',' How, in view of the reason advanced, could they allow mi'un even in marriage! ');">²⁹</span>

Teshuvot Maharam