s 143P Members of a person’s family
(1) For the purposes of this Chapter a person is a member of another’s family if— (a) he is the spouse or civil partner of that person; (b) he and that person live together as a couple in an enduring family relationship, but he does not fall within paragraph (c); (c) he is that person’s parent, grandparent, child, grandchild, brother, sister, uncle, aunt, nephew or niece. (2) For the purposes of subsection (1)(b) it is immaterial that two persons living together in an enduring family relationship are of the same sex. (3) For the purposes of subsection (1)(c)— (a) a relationship by marriage or civil partnership must be treated as a relationship by blood; (b) a relationship of the half-blood must be treated as a relationship of the whole blood; (c) a stepchild of a person must be treated as his child.