Arbitration rests on consent, which makes it difficult to bring all the relevant parties into a single proceeding.
Joinder. Institutional rules permit joinder of an additional party where it is bound by the same arbitration agreement, usually on application before the tribunal is constituted, and with limits afterwards.
Consolidation of separate arbitrations where the agreements are compatible, the disputes arise from the same transaction or series, and the parties consent or the rules permit.
Compatible clauses. In a project with a prime contract and subcontracts, the clauses must match — same institution, same rules, same seat, same number of arbitrators — or consolidation is impossible. This is the single most valuable drafting step in a multi-contract project.
Non-signatories. Bound in defined circumstances through agency, estoppel, assumption, veil piercing, third-party beneficiary and group of companies theories, with the analysis governed by contract law and varying widely.
Appointment in multi-party cases. Where several respondents cannot agree on an appointment, institutional rules typically provide for the institution to appoint the whole tribunal, which removes the imbalance.
Practical consequence. A dispute involving an owner, a contractor and a designer under mismatched clauses proceeds in three forums with inconsistent outcomes and no contribution.