Since both parties participated, submitted to the Dubai court's jurisdiction, and presented their arguments, Indian courts generally view the decree as a decision made on the "merits of the case."

Your son can however file a Civil Suit for Declaration in the Family Court or District Court of Delhi having jurisdiction over his place of residence.

The suit is filed seeking to declare that the foreign judgment dated [2022] passed by the Dubai court is binding, valid, and conclusive under Section 13 of the CPC.

Your son does not necessarily have to fly to India immediately to do this. He can execute a Special Power of Attorney (POA) in favor of you or a trusted relative, get that POA attested by the Indian Consulate in Dubai, and send it to Delhi. You can then hire a family lawyer in Delhi to file the declaration petition on his behalf.