Yosef Karo

“ Seif 6 Someone who purchases a beast need not suspect its mother or child was shechted same day. But it's incumbent on the seller to alert the buyer and inform him if the mother or child was shechted the same day, or if he sold it after he shechted it today. And if it's one of the four times when usually whoever buys a beast shechts it immediately, namely: Erev Pesach, Erev Atzeret, Erev Rosh Hashanah, and Erev Yom Tov Achron of Chag [Pesach] , it's necessary to inform him that today he sold the mother or offspring. ”

“ Seif 8 A deer went on a goat and it gave birth, and he shechted the goat and its kid — he gets lashes. But a goat goes on a deer — it's forbidden to shecht it and its kid, but if he shechted he's not lashed. If that doe's kid was female that bears a buck, and he shechted the doe kid of the deer and its male kid, he gets lashes. ”

“ And if he sold one to the groom and one to the bride: even if he sells on different days he needs to inform them, since they'll surely be shechted the same day. If two people who bought a beast and its offspring the same day, the first buyer should shecht and not the second. ”