You should see Sanhedrin 55b:
>R. Joseph said: Come and hear! A maiden aged three years and a day may be acquired in marriage by coition, and if her deceased husband's brother cohabits with her, she becomes his.
You should see Sanhedrin 55b:
>>R. Joseph said: Come and hear! **A maiden aged three years and a day** may be acquired in marriage by coition, and if her deceased husband's brother cohabits with her, she becomes his.
https://halakhah.com/sanhedrin/sanhedrin_55.html#PARTb
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