Purity: Combining Daily Prayers and Ṣalāt al‑Āyāt
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 429:
Whenever ṣalāt al‑āyāt becomes obligatory for a mustaḥāḍah during the time of the daily prayers and she wants to perform both of them one after the other, then based on obligatory precaution, she cannot perform both of them with one ghusl and wuḍūʾ [and she would need to perform an additional ghusl or wuḍūʾ].
-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)