Question: You said that R. Shimon refers to the Reisha. What does R. Shimon say about Ba'alas ha'Ma'amar?

Answer: We learn from the following [Beraisa]. R. Shimon says, [if Ploni gave a Ma'amar and then a brother was born and Ploni died], Bi'ah or Chalitzah of one of them (i.e. Ploni's other wife) exempts her Tzarah (Ba'alas ha'Ma'amar). If he did Chalitzah to Ba'alas ha'Ma'amar, also the other needs Chalitzah;

Explanation: You say that Bi'ah or Chalitzah of one of them (Ploni's other wife) exempts her Tzarah, for no matter what you will say, [Ba'alas ha'Ma'amar is exempt];

If Ma'amar acquired, both of them are [Ploni's] wives. She is exempt through Chalitzah of her Tzarah;

If Ma'amar did not acquire, the first does not need Chalitzah (she is Eshes Achiv she'Lo Hayah b'Olamo).

If he did Chalitzah to Ba'alas ha'Ma'amar, also the second needs Chalitzah. Perhaps Ma'amar did not acquire, and Chalitzah or Yibum did not apply to the first (she was Eshes Achiv she'Lo Hayah b'Olamo, so it was not Chalitzah);

Perhaps Ma'amar acquired, and she was exempted through Chalitzah of her Tzarah.

Question: What is the difference between them? (Also Rabanan say that the second does Chalitzah!)

Answer #1: [They argue about] if he did Chalitzah to the first and had Bi'ah with the second. According to Rabanan, this is Bi'as Ervah (she is partially Tzarah Eshes Achiv she'Lo Hayah b'Olamo). According to R. Shimon, it is not Bi'as Ervah. (If Ma'amar did not acquire, it is proper Yibum. If Ma'amar acquired, this is Bi'ah after Chalitzah of a Tzarah. Reish Lakish holds that it is only a Lav. And even those who say that there is Kares, it is not Vadai Kares, for perhaps Ma'amar did not acquire. We explained this like HA'GAON RAV C. KANIEVSKY, SHLITA.)

Answer #2: [They argue about] if he had Bi'ah with the first and had Bi'ah with the second. According to Rabanan, the first is Bi'as Ervah (Eshes Achiv she'Lo Hayah b'Olamo). The second needs a Get and Chalitzah (it was a Pasul Yibum);

According to R. Shimon, both of them need a Get. The first needs a Get, for perhaps Ma'amar acquired (and it was proper Yibum). The second needs a Get, for perhaps Yibum acquired (i.e. if the Ma'amar did not acquire, so only the second fell to Yibum. She does not need Chalitzah if the Yibum was proper, and even) if the Ma'amar acquired (Bi'ah of the first was proper Yibum, so) she was exempted from Chalitzah through Bi'ah of the first.

(R. Ze'orah citing R. Sheshes): It was taught there that R. Shimon says, [if Ploni gave a Ma'amar and then a brother was born and Ploni died], both of them (also Ploni's other wife) are forbidden.

Question: If Ma'amar acquired, both of them are permitted;

[And] if Ma'amar did not acquire, and [there is only] Zikah, [also] this is difficult!

If Zikah acquired (as if he did Yibum), both of them are permitted;

[And] if Zikah did not acquire, the first is forbidden (Eshes Achiv she'Lo Hayah b'Olamo), and the second is permitted (she alone fell to Yibum from Ploni)!

Answer: Perhaps Zikah according to R. Shimon is like Ma'amar according to Rabanan. Just like Rabanan say that it acquires [partially] and leaves over, so Zikah acquires and leaves over. (We explained this like PNEI MOSHE.)

Question: The part that Zikah acquires, correspondingly is permitted in the Tzarah (to that extent she is the Tzarah of a permitted wife, i.e. Eshes Achiv she'Hayah b'Olamo). The part that Zikah does not acquire, correspondingly is permitted in the Tzarah (to that extent, she alone fell to Yibum from Ploni. Why is the Tzarah forbidden?)

Answer (R. Shamai): Do we say 'miMah Nafshach' (either way you will say) in Arayos?! (We do not!)

Question: What is the reason?

Answer: It is like R. Acha taught in the name of R. Bun bar Chiyah - any Yevamah who is not totally inside (permitted to do Yibum), the part of her that is acquired is judged like Ervah, and Ervah exempts her Tzarah. (We explained this like SEFER NIR.)