Talmud zu Ketubot 1:4

HALAKHAH: “If an underage levir,” etc. ¹²³The entire paragraph is from Ketubot Halakhah 1:4. It was stated: A claim of non-virginity may be brought within thirty days, the words of Rebbi Meїr. But the Sages say, immediately¹²⁴In the Babli, 111b, and the Tosephta, Ketubot 1:4: “A claim of non-virginity may be brought within thirty days, the words of Rebbi Meїr. Rebbi Yose says, if they were alone together, immediately; if they were not alone together, within thirty days (Tosephta), indefinitely (Babli).”
The husband goes to court to annul the marriage, without divorce and without payment, claiming that he was lead to believe the bride to be a virgin when he found that she was not.. Where do we hold? If he copulated, immediately. If he did not copulate, even after a longer delay. But we must hold if it was not spelled out. Rebbi Meїr said, it is credible that a man may hold himself back for thirty days. But the Sages say, a man does not hold himself back even for one day¹²⁵In the Babli, 112a, this is declared to be irrelevant for our Mishnah since a man will sleep with his bride immediately after the marriage ceremony but might be reluctant to touch his sister-in-law for some time.. Rebbi Jeremiah asked: According to Rebbi Meїr, would a man be believed to assert that he held himself back for thirty days in order to make the child fatherless¹²⁶If his wife becomes pregnant immediately after the marriage ceremony, can he declare in court that the child is not his since he did not sleep with his bride for some time?? Let us hear from the following: “If the sister-in-law claims within thirty days that she was not copulated with, one forces him to perform ḥalîṣah with her. After thirty days, one asks him to perform ḥalîṣah with her.” (After thirty days.)¹²⁷Missing in Ketubot. And Rebbi Eleazar said, this is Rebbi Meїr’s¹²⁸But the majority will accept the widow’s claim only on the day after she entered the levir’s house.. And Rebbi Eleazar said, that refers only to her, but not to her co-wife¹²⁹If the co-wife married an outside man based on the other’s levirate marriage, she cannot cast aspersion on the validity of her cowidow’s marriage without the testimony of two credible witnesse.
The Babli agrees, 112a, at least in the interpretation of Rashi and Rabbenu Ḥananel.. As you say there¹³⁰“There” is here, Yebamot, “here” is there, Ketubot, cf. Note 122., she is not believed to damage her co-wife, so here, he is not believed to damage his son.