Judgment of the Court (Third Chamber) of 12 March 2026.#BC, légalement représenté par sa représentante légale v LG.#Reference for a preliminary ruling – Area of Freedom, Security and Justice – Judicial cooperation in civil matters – Regulation (EC) No 4/2009 – Jurisdiction in matters relating to maintenance obligations – Article 12 – Lis pendens – Determination of the court first seised – Article 9(a) – Concept of an ‘equivalent document’ with regard to a document instituting the proceedings – Submission of an application for legal aid before a court of a Member State by a maintenance creditor with a view to bringing an action for the variation of maintenance obligations owed to him or her – Subsequent application submitted by the maintenance debtor to vary his or her maintenance obligations before a court of another Member State – Subsequent action by the maintenance creditor before the first court after that court has granted legal aid – Classification of that application for legal aid as an ‘equivalent document’