6. For section 123(3) (claim to share right to buy with members of family) substitute—
“(3) Where by such a notice any members of the qualifying person’s family are validly required to share the right to buy with him, the right to buy the qualifying dwelling-house belongs to the qualifying person and those members jointly and they shall be treated as joint tenants for the purposes, in relation to that qualifying dwelling-house, of the right to buy.”