Section 54: Institution of proceedings.

(1) Subject to the next succeeding subsection, a matrimonial cause of a kind referred to in paragraph (a) or (b) of the definition of "matrimonial cause" in section 114(1) of this Act shall be instituted by petition.
(2) A respondent may, in the answer to the petition, seek any decree or declaration that the respondent could have sought in a petition.
(3) Proceedings of a kind referred to in paragraph (c) of the definition of "matrimonial cause" in section 114(1) of this Act that are in relation to proceedings under this Act for a decree or declaration of a kind referred to in paragraph (a) or (b) of that definition-
(a) may be instituted by the same petition as that by which the proceedings for that decree or declaration are instituted; and
(b) except as permitted by the rules or by leave of the court, shall not be instituted in any other manner.
(4) The court shall, so far as is practicable, hear and determine at the same time all proceedings instituted by the one petition.