The necessity of making all co-owners parties in a partition suit is essential for maintaining the validity of the decree.

1. This appeal is preferred by defendant - appellant against an appellate judgement and decree affirming the decree of the trial Court passed in an instituted suit of the plaintiff - respondent.

2. We need not recite the facts of this case over again because they are sufficiently stated in the judgement of the appellate court below. Brief outline of the case, however, is that the appellant obtained a declaration and a decree for partition of her 1/3rd share in the disputed properties in a suit brought by her sometime in 1947. The respondent company which took lease of the disputed property from the rest of her co - sharers by different documents executed sometime between 1948 and 1951 during pendency of the partition suit brought subsequently the present suit only against the appellant for setting aside the partition decree and for other reliefs mainly on the ground of fraud and non - joinder of parties. The suit was contested by the appellant and apart from the general denial of material allegation of fraud in the plaint, in her written statement she challenged the maintainability of the suit on the principle of res judicata and lis pendens as also the right and status of the plaintiff to institute such a suit. The trial court decreed the suit. The learned appellate court in agreeing with the trial court took the view, firstly, that the partition decree was passed in absence of one co - sharer namely Radharani Devi; secondly, the appellant brought all heirs and legal representatives of one of the co - sharers on making a false statement of the date of his death at the first appellate stage of that suit and thus obtained decree by practising fraud on court; thirdly, the family deity who was interested in the properties covered by the partition suit was admittedly not made party in that suit and as the shebaits of the deity granted lease of such properties to the respondent at the material time, partition decree could not be held to be binding on it. Accordingly, the learned appellate court affirmed the decree of the trial court and that is how in short the appellant felt aggrieved and preferred the present appeal.

3. Before we enter into the merits, we must notice that on the admitted position of the parties, the plaintiff - respondent was only a lessee from other co - sharers. It had therefore a subordinate and not co - ordinate interest in respect of the disputed properties in relation to the appellant. The question is whether such a suit for setting aside a partition decree in respect of joint immovable properties in which the respondent had merely a subordinate interest in absence of other co - sharers who had and still retain their interests as lessors in such properties is maintainable without making them parties in the suit. In the partition suit, the present respondent was not necessary party, more so, when all the leases in its favour were admittedly granted during pendency of the partition suit. If, therefore, its lessors have suffered a decree for partition, we think, apart from the other questions such a suit would not be maintainable without making its co - sharers lessors parties in the present suit. The interest of such co - sharers lessors not being identical with that of the respondent in the disputed property they would become necessary and not merely proper parties in the present suit. It is well established that a suit or any proceeding must fail by reason of non - joinder of parties. For, although provision of O.1 R.9 of the Code of Civil Procedure is a Rule of procedure not affecting the substantive law, n