cellio | daf bit: Yevamot 40

We're still talking about the levirate marriage, where if a married man dies without having fathered a child his brother is expected to marry his wife. A mishna on today's daf teaches: if a man (who isn't disqualified for some other reason) refuses that marriage, then he is not permitted to marry the wife's relatives -- mother, grandmother, daughter, granddaughter, or (while she's alive) sister. (He's done with that family, in other words -- if he won't marry his brother's wife then he can't try for someone else therein.) The other brothers in the family are under no such restriction; they may freely marry her relatives (but not her). She is also forbidden to marry the rejecting brother's relatives (father, brothers, sons, etc). (40a-b)