This section sets out when persons are to be regarded as not forming a single household for the purposes of section 254.
Persons are to be regarded as not forming a single household unless—
they are all members of the same family, or
their circumstances are circumstances of a description specified for the purposes of this section in regulations made by the appropriate national authority.
For the purposes of subsection (2)(a) a person is a member of the same family as another person if—
those persons are married to , or civil partners of, each other or live together as if they were a married couple or civil partners;
one of them is a relative of the other; or
one of them is, or is a relative of, one member of a couple and the other is a relative of the other member of the couple.
For those purposes—
a "couple" means two persons who ... fall within subsection (3)(a);
"relative" means parent, grandparent, child, grandchild, brother, sister, uncle, aunt, nephew, niece or cousin;
a relationship of the half-blood shall be treated as a relationship of the whole blood; and
the stepchild of a person shall be treated as his child.
Regulations under subsection (2)(b) may, in particular, secure that a group of persons are to be regarded as forming a single household only where (as the regulations may require) each member of the group has a prescribed relationship, or at least one of a number of prescribed relationships, to any one or more of the others.
In subsection (5) "prescribed relationship" means any relationship of a description specified in the regulations.