After section 29(2) of the Principal Act insert —
"(3) A person does not commit an offence against subsection (1) if—
(a) the person carries out a treatment procedure using gametes, or an embryo formed from gametes, produced by a donor; and
(b) the person knows the treatment procedure may result in more than 10 women having children who are genetic siblings; and
(c) the treatment procedure is carried out—
(i) on a woman who has a female partner or whose female partner is deceased to produce a child who will be a genetic sibling of the children of that woman and her partner or that woman and the deceased (as the case requires); or
(ii) on a woman under a surrogacy arrangement to produce a child who will be a genetic sibling of the children of—
(A) both commissioning parents; or
(B) the commissioning parent, if the other children of the commissioning parent were born as a result of a surrogacy arrangement commissioned only by that commissioning parent; or
(C) in the case of posthumous use, the commissioning parent and the deceased.".