Ketubot, Chapter Twelve, Mishnah One
This mishnah deals with a case where a widow who already had a daughter married a man and cut a deal with him that he provide food and clothing for this daughter for five years.
1) If a man married a woman and she cut a deal with him that he should maintain her daughter for five years, he must maintain her for five years.
2) If she was [subsequently] married to another man and cut a deal with him [as well] that he should maintain her daughter for five years, he must maintain her for five years.
a) The first husband may not plead, If she will come to me I will maintain her, rather he must send her maintenance to her at the place where her mother [lives].
b) Similarly, the two husbands cannot plead, We will maintain her jointly, but one must maintain her and the other give her the cost of her maintenance.
Section one: Since he promised to maintain her for five years, he is obligated to do so, no matter what the circumstances, as we shall see below.
Section two: If this woman is divorced from this husband and goes and gets married again, and then cuts a deal with the new husband that he should maintain the daughter for five years, the first husband is still obligated, even though the daughter will now receive maintenance from the second husband.
The first husband may not say that he will maintain her only if she comes back to live with him. Even though the first husband intended to maintain her so that he could be married to her mother, he is still obligated. If necessary he must send her maintenance money to wherever she may be.
Finally, the two husbands cannot split the costs of the daughters maintenance. Rather each one must bear the full costs; one provides the actual food and clothing and another provides the monetary equivalent.