If one said to a woman: You are sanctified to me with this penny after thirty days, then even if the money was used up before the end of the thirty days she is indeed sanctified after thirty days; and if he went back on his statement within the thirty days, or she went back on hers, she is not sanctified. Note: and there are those who say that if he sanctified her with a document and does not have it after the thirty days, but it was torn or lost within the thirty, then she is not sanctified (the R'aN, chapter "The one who says."). One who sanctifies a woman over thirty days, she is always sanctifed. (ibid)
If a second man came and sanctified her within the thirty days, then she is always sanctified to the second one, since at the time that the second one sanctified her she was not sanctified, so that the sanctification of the second one affected her and she became a married woman, and when the thirty days passed so that the sanctification of the first man arrived, it found her a married woman already, and the first one was in the position of one who sanctifies an already-married woman, and his sanctification does not affect her. But if the second one should die or divorce her within the thirty days, the first one's sanctification comes back into effect (Tur according to 'some say'), and therefore she needs a divorce document from the first one [before accepting the sanctification of the second]; but some disagree (Tur according to the Rosh).
One who says to a woman, "You are hereby betrothed to me with this coin, from now and for after thirty days," and someone else came and betrothed her within thirty days, she is doubtfully betrothed to both of them. Therefore, they both give her a bill of divorce, whether within the thirty days or after the thirty days.
He said to her: behold, you are betrothed to me from now and for third days after, and another came and said: behold, you are betrothed to me from now and for twenty days after, and another came and said: behold, you are betrothed to me from now and for ten days after, even if a hundred [men came] in this order, the kiddushin of all of them are incumbent on her and she needs a get from each one of them, because she is doubtfully betrothed to all of them.
The one who says to his wife: behold you are betrothed to me by this prutah after I will convert [to Judaism], after you will convert [to Judaism], after I am freed, after you are freed, after your husband dies, after your sister dies, she is not [considered] betrothed, because he is not able to betroth her now.
The one who says to a childless widow [awaiting levirate marriage]: behold you are betrothed to me by this prutah after [the other man] releases you of your levirate [status], behold she is doubtfully betrothed.
The one who gives two prutahs to a woman, and he said to her: behold you are betrothed to me with one [prutah], and with one [prutah] after when I will divorce you, behold she is betroths, and when he divorces her, she will be betrothed. But if he gave a prutah to a married woman and he said to her: behold, you are betrothed after you divorce [him], or if he gave a prutah to his wife and he said to her: behold, you are betrothed to me after I divorce you, it is not anything.
The one who says to his friend: if your wife gives birth, [if it is] a girl she will be betrothed to me, it is not anything; and for the Rambam and a few of the commentators, if she was the pregnant wife of his friend and he recognized the fetus, the daughter is betrothed, and he needs to go back and betroth her from her father after she is born, because when oneenters into kiddushin they do not have a defect.