21. Before the parties to a civil partnership can change their civil partnership into a marriage in accordance with this Chapter each of the parties must sign a declaration containing—
(a)the following details pertaining to each of the parties—
(i)forename(s);
(ii)surname;
(iii)nationality;
(iv)date of birth;
(v)sex;
(vi)address; and
(b)a statement to the effect that—
(i)each of the parties has had, for the period of 28 days ending on the day on which the change is to be completed, their usual residence within the consular district of the registration officer;
(ii)the parties are in an existing civil partnership with each other;
(iii)each of the parties knows of no reason why the civil partnership should not be changed into a marriage.