What is the implication if a third partner agrees with the client in a declaratory judgment matter?

In a declaratory judgment matter, the involvement of a third partner who agrees with the client signifies that the third partner has a stake in the outcome of the case. In the context of procedural requirements, this agreement indicates that their interests are directly implicated in the declaratory judgment being sought. Therefore, they should be joined as a plaintiff in the action to ensure that all parties with an interest in the legal relationship or the issue at hand are represented.

Joining the third partner as a plaintiff serves an essential purpose: it not only aligns with the principles of complete relief and the avoidance of multiple suits but also ensures that the court's ruling will be effective and comprehensive. The court seeks to resolve disputes fully and fairly, and not including all interested parties could lead to incomplete determinations or repeated litigation, which is contrary to the objectives of judicial economy.

The other considerations outlined in the other options do not serve the objective of ensuring all interested parties are represented in a case. Thus, the requirement for the third partner to be joined as a plaintiff reflects the procedural rules designed to promote fairness and comprehensive resolution of disputes in declaratory judgment actions.