But when the suit has been filed the trial judge becomes dominus litis and then assumes, under Order IV Rule 5(1) of the High Court Rules, Cap 61 of the Laws of Eastern Nigeria 1963 still operative in the Rivers State, the duty and responsibility to ensure that the proceedings accord with the justice of the case by joining either as plaintiff or defendants all the persons who may be entitled to, or who claim some share or interest in the subject-matter of the suit, or who may be likely to be affected by the results if these had not already been made parties. This joinder by the Court suo motu can be done at any state of the proceedings.
– Oputa, JSC. Green v. Green (1987)