Read Luke 2:44 Using Other Translations
But they, supposing him to have been in the company, went a day's journey; and they sought him among their kinsfolk and acquaintance.
but supposing him to be in the group they went a day's journey, but then they began to search for him among their relatives and acquaintances,
because they assumed he was among the other travelers. But when he didn’t show up that evening, they started looking for him among their relatives and friends.