If a house collapsed on (and killed) Reuven and his father (Shimon) or on Reuven and on someone who he would inherit (e.g., his brother Levi) and Reuven had upon him (the claim of) his wife's kesuvah and a creditor...

If the heirs of the father say that the son died first and then the father (so that kesuvah money or debt was never owned by the son); and the creditors say the father died first and then the son (so that they can collect the debt from the estate of the son...

Beis Shammai: They divide the estate.

Beis Hillel: It remains in its original state (and the creditors must bring proof that the father died first).

If a house collapsed on (and killed) a man and his wife, and the man's heirs say that she died first (so he inherited all of her property), and her heirs say that he died first (so they inherit her property and her kesuvah)...

Beis Shammai: They divide it.

Beis Hillel: All of the property remains in its original state - the kesuvah remains in the possession of the heirs of the husband and the property that comes in and goes out with her (the property she had inherited from her father and brought with her into the marriage) remains in the possession of the heirs of the father (meaning her heirs).

If a house collapsed on a man and his mother - both Beis Shammai and Beis Hillel agree that they divide it.

R. Akiva: I agree in that case that the property remains in its original state.

Ben Azai to R. Akiva: When there was a disagreement it upset us and you wish to disagree when there is no disagreement?!

(Gemara) - R. Shmuel bar Rav Yitzchak: This proves that Ben Azai was student but also a contemporary of R. Akiva (as otherwise he would have referred to him as 'Rabbeinu').