Does the Imam's sutrah serve as a sutrah for those who join the prayer late, after the Imam has concluded, or are they required to take a new sutrah?

If a latecomer (masbuq) stands up to make up for what he missed after the Imam has concluded the prayer, he is considered to be praying alone, and he must prevent anyone from passing in front of him. This is based on the command of the Prophet, peace and blessings be upon him, regarding this matter. The fact that he joined the congregation does not change the ruling of his being alone when making up for what he missed.