Related for Ketubot 217:3
על מה נחלקו על שפסקה היא על עצמה שחכמים אומרים תשב עד שתלבין ראשה אדמון אומר יכולה היא שתאמר כסבורה אני שאבא נותן עלי ועכשיו שאין אבא נותן עלי מה אני יכולה לעשות או כנוס או פטור אמר רבן גמליאל רואה אני את דברי אדמון
They only disagree where she herself promised a sum of money on her own behalf, in which case the Sages ruled: Let her remain [single] until her hair grows grey, while Admon says that she could say, “I thought that my father would pay for me [the promised amount], but now that my father does not pay for me, what can I do? Either marry me or set me free.” R. Gamaliel said: I see Admon’s words.
Tosefta Ketubot
Said Rabbi Yose son of Rabbi Yehudah: Admon and Hakhamim did not disagree (in Mishnah Ketubot about one whose father agreed [to add money in the dowry] for her that she is able to say: "My father agreed [this money] for me. What am I able to do? Either marry me or divorce me!" Regarding what [case] did they disagree? When she agreed to pay it herself. Admon says: She is able to say: "I thought my father would pay me, but now that my father is not paying me, what am I able to do? Either marry me or divorce me!" Said Rabban Gamliel: I agree with the words of Admon. One who agreed money for his minor daughter [in her dowry] and then tried to weasel out of it, they force him to pay, for one can act [in a minor's] favour but not to their detriment.
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