If the Pesach was lost, and was found before the Slaughtering of its replacement: Pesachim 96b, 97a-b
Above, where it was found after the Slaughtering of its replacement: Pesachim 96b, 97b
Above two cases, where it was found before/after midday: Pesachim 96b, 97b
A Pesach Offering which is lost and found before the time when it could be brought: Pesachim 97a-b
If one took 2 animals, one to be a stand-in for the Pesach Offering: Pesachim 97b
Requiring that there be more than one individual designated on a Pesach Offering, at the time of its Slaughtering: Pesachim 99a
Requiring that a Pesach Offering always have at least one owner, perhaps even that he be from the original designators of the animal: Pesachim 99a
If the owner died after taking an animal to be a Pesach Offering: Pesachim 98a [2x]
Above case, for the son to use it: Pesachim 98a