YES you can as your BROTHER'S WIFE'S BROTHER DAUGHTER‘ does not fall under Sapinda relationship.
The restriction is only from father side seven degrees of prohibited relationships’ and from mother side five degrees of prohibited relationships’.
Section 3(g) of the Hindu Marriage Act, 1955 defines ‘degrees of prohibited relationships’. It provides as follows:
Lineal ascendants are to be seen from both sides, i.e. from the father’s side as well as from the mother’s side. So both the father and mother are lineal ascendants. Similarly father’s father is a lineal ascendant whereas mother’s mother is also a lineal ascendant. But a paternal grandmother is not a lineal ascendant but the wife of a lineal ascendant and hence would fall under clause ii. Similarly a maternal grand-father would fall under clause ii being the husband of a lineal ascendant. Clause ii would also cover daughter-in-law and son-in-law being the wife and husband respectively of one’s lineal descendants i.e. son and daughter respectively. A paternal Aunt (Chachi) and a maternal Aunt (Maami) would fall under clause iii and two siblings along with other relations described in clause iv also fall in degrees of prohibited relationships.
Sapinda relations:
Section 3(f) defines ‘Sapinda relationship’ as under:
Sapinda relations can be illustrated as under:
Suppose A is a boy. Now if he is considered as one generation, relatives falling in four more generations upwards from him from the side of his father shall be his Sapinda relations. Therefore, A’s father, A’s grand-father, A’s great grand-father and the father of A’s great grand-father shall all be A’s Sapinda relations. But on the mother’s side, this chain is to extend to only three generations which include A. Therefore, A’s mother and A’s maternal grand-mother only shall be A’s Sapinda relations from the mother’ side, A himself being one generation.
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