If someone arrives late on Shabbat and the congregation is already praying Musaf, may he pray Musaf before Shacharit?

This source-based Torah study examines: If someone arrives late on Shabbat and the congregation is already praying Musaf, may he pray Musaf before Shacharit? It follows the canonical Hebrew discussion and the classical sources cited there, preserving the distinctions and review status of the original. This localized layer is for study and discovery only; it is not practical halakhic, legal, military, medical, safety or pastoral advice.