Relative

Definition of relative is given in sec 2(41) Of Companies  Act,1956 and not in  that  of  I.T Act ,1961.

yes , son in law will fall under that defintion of relative because the said sec provides that relative includes spouse of children of a person.

Sec 2 (41) of Income tax act

“relative”, in relation to an individual, means the husband, wife, brother or sister or any lineal ascendant or descendant of that individual ;

Therefore it does not include Son in law