English to Polish Law/Patents Law (general)

in the text which i am working on together with 3 other people it occurs in different contexts. in the bit i am working on it appears in the context of three arbitration proceedings with identical claims and one of the parties argues that should Claimant be successful in all three arbitrations it would obtain much more than it would in one only. i am inclined to think that "necessary joinder" in this context means "połączenie powództw", the more so that in the next paragraph, which goes as follows: "In its additional submissions on the rules of international arbitration in XYZ and on the substantive laws applicable to the issue of necessary joinder of all ABC shareholders, Respondent posits that the issue of mandatory participation must primarily be considered under XYZ law", both "necessary joinder" and "mandatory participation" (presumably joint participation). thus, we have "necessary joinder" and "mandatory participation". in the rmaining part of the document my friends are working on, necessary joinder seems to be used in the meaning of "mandatory participation" and we are slightly confused. i shall be grateful for feedback