What is the ruling on praying the Sunnah of Maghrib and Isha, and Witr, after combining the Maghrib and Isha prayers at the time of Maghrib due to difficult weather conditions?

The time for the post-prayer ratibah (supererogatory) prayer begins after the completion of the obligatory prayer it follows. Therefore, it is permissible for someone who combined Isha with Maghrib to pray the ratibah of Maghrib and Isha at that time. It is sunnah (definition) to separate the obligatory prayer from the supererogatory prayer by moving or speaking, based on the statement of Mu'awiyah (may Allah be pleased with him): "Indeed, the Prophet (peace be upon him) commanded us that we should not join one prayer to another until we speak or move out." As for Witr prayer, its time begins for the Hanafis and Malikis after the Isha prayer and the disappearance of the twilight. For the Shafi'is and Hanbalis, it begins only after the Isha prayer. The more cautious approach is to delay Witr until the disappearance of the twilight.