(R. Avahu citing R. Yosi ben Chaninah): Every Misah that [for a Bas Yisrael] is less [stringent] than that for [Zenus with] her father, (i.e. Sereifah, e.g. a Nesu'ah Bas Yisrael gets only Chenek; such a Bas Kohen gets) Sereifah;

When she is with her father (Arusah, a Bas Kohen is like a Bas Yisrael - for Zenus) with her father she gets Sereifah, and [for Zenus] with her father-in-law [or a stranger] she gets Skilah. (This is like Rabanan.)

Note: Why is her Misah lighter for Zenus with her father than for with a stranger? This must be like R. Yosi (below, Mishnah 9:4) who says that she is punished for the first Chiyuv that came. She was Asur to her father from birth; when she became Mekudeshes later, regarding her father Ein Isur Chal Al Isur. According to the Bavli (Yevamos 34a), this is only if she became Mekudeshes after the age of three or 12 - see Tosfos there, DH mi'Toch.

(R. Eliezer): Es Aviha Hi Mechaleles ba'Esh Tisaref - if [a Bas Kohen] is with her father (Arusah), she gets Sereifah (one level above a Bas Yisrael, who gets Skilah), and if she is with her father-in-law (Nesu'ah), she gets Skilah (one level above a Bas Yisrael, who gets Chenek; this is like R. Shimon. So Rava explains R. Eliezer in the Bavli (51b) - ZAHAV HA'ARETZ.)

She (a Bas Kohen) gets Sereifah, but the man who had Bi'ah with her does not get Sereifah, and Edim Zomemin [through whom she was sentenced to Sereifah] do not get Sereifah.

[When do Edim Zomemin get the same Misah? It is when the Bo'el gets the same Misah as she does. If [the corresponding man, i.e. the Bo'el] gets Sereifah like [the Niv'eles], he and they (Edim Zomemin) get Sereifah. If he gets Skilah like her, he and they get Skilah. If he gets Chenek [and she is a Bas Kohen], she gets Sereifah and he and [the witnesses] get Chenek.