joinder

/ˈdʒɔɪndər/
noun
  1. The act of joining or bringing together; in law, the joining of parties or issues in a legal case.
    • The joinder of the defendants was necessary to avoid multiple trials.
    • The lawyer filed a motion for joinder of the additional claims.
    • The court allowed the joinder of the two lawsuits because they involved the same accident.