Completing missed rakats as a latecomer to Zuhr

Answer

See fatwa: the masbuq (latecomer) makes up the beginning of his prayer with respect to recitation, but its ending with respect to the sitting order — what he prayed with the imam is considered the latter part concerning recitation and tashahhud.

Al-Hidayah: *وَمَا أَدْرَكَ الْمَسْبُوقُ مَعَ الْإِمَامِ فَهُوَ آخِرُ صَلَاتِهِ، وَمَا يَقْضِي بَعْدَ سَلَامِ الْإِمَامِ أَوَّلُ صَلَاتِهِ* — "Whatever the masbuq catches with the Imam is the latter part of his prayer, and whatever he completes after the Imam's salam is the beginning of his prayer." Practical rulings from al-Fatawa al-Hindiyyah: if he caught three rakats of a four-rakat prayer, he completes one rakat with recitation (al-Fatiha and a surah) and sits; if he caught two rakats, he completes two rakats reciting al-Fatiha and a surah in both, sitting after the first; if he caught one rakat, he completes three, reciting in the first two, sitting after the first, and reciting only al-Fatiha in the third. Regarding catching rukuʿ, al-Quduri states whoever catches the Imam in rukuʿ and performs rukuʿ with him, that rakat counts for him.