Who can seek declaration for third parties in arbitration?

X, under an agreement with Y, was to construct a residential complex within a set time. Some flats were sold during construction. A High Court status quo order halted construction, and Y later terminated the contract. Y has now invoked arbitration and seeks a declaration from the Arbitral Tribunal regarding X’s liability towards the homebuyers (who are not parties to the agreement). Can Y legally seek such a declaration?