Gemara

(Beraisa - Rebbi): If a Yavam gave a Ma'amar to a Yevamah against her will, he acquired her;

Chachamim say, he did not acquire her.

Rebbi learns from Yibum. Just like Yibum acquires her against her will, also Ma'amar;

Chachamim learn from Kidushin. Just like Kidushin requires her consent, also Ma'amar.

Rebbi holds that it is better to learn matters of a Yevamah from matters of a Yevamah;

Chachamim hold that it is better to learn from Kidushin (because Ma'amar makes Kidushin).

Kidushin 41a (Mishnah): A man can Mekadesh his daughter when she is a Na'arah.

43b (Mishnah): One can divorce a Na'arah Me'urasah by giving the Get to her or to her father;

R. Yehudah says, we never find that each of two people has jurisdiction over one person. Rather, only her father can receive it.

(Reish Lakish): Chachamim and R. Yehudah argue similarly about who can receive Kidushin for a Na'arah (only the father, or also herself);

(R. Yochanan): They argue only about divorce. All agree that only her father can receive her Kidushin.

(R. Yosi bar Chanina): R. Yochanan explains Chachamim as follows: when a girl is divorced, she returns herself to her father's jurisdiction, so (also) she can receive her own Get. When she becomes Mekudeshes, she extracts herself from her father's jurisdiction, so only he can receive her Kidushin.

Question: A Ma'amar (Kidushin of a Yevamah) extracts a girl from her father's jurisdiction, yet a Na'arah can receive it herself!

(Beraisa #1): If a minor fell to Yibum from Kidushin, a Ma'amar requires her father's consent;

If she is a Na'arah, it requires her consent or her father's.

Answer (#1): Rather, R. Yosi bar Chanina taught that R. Yochanan explains Chachamim as follows. A girl becomes Mekudeshes only willingly, therefore only the father can receive Kidushin;

She can be divorced against her will, therefore even she can receive the Get.

Question: A Ma'amar requires consent, yet she can receive it herself!

Answer (#1): Beraisa #1 is like Rebbi, who holds that a Ma'amar works against her will.

(Beraisa - Rebbi): If a Yavam gave a Ma'amar to a Yevamah against her will, he acquired her;

Chachamim say, he did not acquire her.

Question (against Reish Lakish - Seifa of Beraisa #1): (One needs consent of a Na'arah or her father to give a Ma'amar.) This is not true regarding Kidushin.

Answer: Perhaps Beraisa #1 is R. Yehudah, who says that two people never have jurisdiction over one person.

Question: If so, why does it say 'this is not true regarding Kidushin'? It should say, 'this is not true regarding divorce' (this is a bigger Chidush)!

Answer: Even though that is a bigger Chidush, since the Beraisa discusses Ma'amar, it mentions Kidushin, which is similar to Ma'amar.

Question: According to R. Yehudah, why is Ma'amar different than Kidushin?

Answer: It is different because she is already partially acquired to the Yavam.

Answer #2 (Rashi - to Question (10); Tosfos Ri ha'Zaken - to Question (13)): A Na'arah can receive a Ma'amar herself because she is already partially acquired to the Yavam.

Rishonim

Rif and Rosh (Kidushin 18a and 2:5): The Halachah follows R. Yochanan, who says that all agree that only her father can receive her Kidushin.

Ran (DH k'Machlokes): This is because Kidushin requires the consent of the Makneh (the one who gives the merchandise).

Rosh (last four lines of 2:7 and 2:8): BaHaG says that if her father went overseas and her mother married her off, it is a valid marriage. This is included in Chachamim's enactment of marriage for a girl without a father. When she matures, it becomes mid'Oraisa. When the father comes, no other Kidushin is needed. The She'altos says that the marriage mid'Rabanan is only when there is no father. It seems that they argue, but this is not certain. Perhaps the She'altos discusses when the father is here. However, this is difficult, for the Gemara (44b) struggled to find a case of a girl who became married without her father. It should have said that he went overseas! Some forbid her to get married in her father's absence, lest her father will Mekadesh her to someone else. It seems that she is permitted, for at any moment we are not concerned lest he already was Mekadesh her.

Beis Shmu'el (EH 37:29): He seems to say that if the father comes after she matured, no other Kidushin is needed because it became mid'Oraisa. However, after she matured the father has no jurisdiction over her! Rather, he must discuss when he came before Bagrus.

Rambam (Hilchos Ishus 3:11): A man can Mekadesh his daughter to a man without her consent as long as she is a minor. (Also) when she is a Na'arah he has jurisdiction over her - "Es Biti Nosati l'Ish ha'Zeh". Therefore he can Mekadesh her from her birth until Bagrus. Even if she is deaf or a lunatic, he makes her a full Eshes Ish.

Rambam (13): If a girl accepted Kidushin before Bagrus, she is not Mekudeshes.

Rambam (Hilchos Yibum 2:1): If one gave a Ma'amar to his Yevamah b'Al Korchah it is void, for a woman becomes Mekudeshes only willingly. If a minor fell to Yibum from Kidushin, a Ma'amar requires her father's consent.

Magid Mishneh: The laws of Ma'amar are like those of Kidushin.

Poskim

Shulchan Aruch (EH 37:1): A man can Mekadesh his daughter to a man without her consent as long as she is a minor. Also when she is a Na'arah he has jurisdiction over her. Therefore he can Mekadesh her from her birth until Bagrus Even if she is deaf or a lunatic, he makes her a full Eshes Ish.

Shulchan Aruch (4): If a girl accepted Kidushin before Bagrus without her father's Da'as, she is not Mekudeshes.

Shulchan Aruch (14): If a minor's father went overseas and her brothers or mother married her off, she is Mekudeshes. She needs Mi'un to leave him. When the father comes, no other Kidushin is needed. Some say that it is not Kidushin and Mi'un is not needed.

Aruch ha'Shulchan (21): The Mordechai says that it is Kidushin only if due to poverty he left his house empty, for then he is happy that his wife found a proper husband. If he went on business, he does not want Kidushin without his consent. It is possible that we are concerned lest the father consents only when he is away, and she needs a proper Get. Most disagree with this.

Chelkas Mechokek (27): The Ran says that it is proper to be stringent, for some are concerned lest her father be Mekadesh her overseas.

Shulchan Aruch (166:3): A Ma'amar requires the Yevamah's consent. If she is a minor who fell to Yibum from Kidushin, it requires her father's consent.

Beis Yosef (DH u'Mah she'Chosav): The Halachah does not follow Rebbi against Chachamim. A Beraisa (Yevamos 19b) is like Chachamim.

Prishah (7): Since Ma'amar can be given properly through her father, it must be done through him. If she fell from Nisu'in, she is out of his Reshus. Perhaps it can be done through her brothers or mother.

Taz (3): It can be done through her brothers or mother.

Aruch ha'Shulchan (15): If she fell from Nisu'in, they must wait until she matures in order to enable a Ma'amar. Alternatively, perhaps since Yibum is permitted b'Al Korchah even if she is a minor, also the Ma'amar.