Reference for Ketubot 213:11

אמר רב ששת במשרה את אשתו ע"י שליש אי הכי בניו ובנותיו נמי כשהשרה לזו ולא השרה לזו מאי פסקא

Sheshet said; [Here it is a case] where a husband maintained his wife at the hands of an agent. If so, they should also provide for his sons and daughters? [It is a case] where [a husband] made provision for the maintenance for her but not for them. How can we be so certain?

Jastrow