Is it permissible to change one's intention during prayer if one remembers that the previous prayer was missed?

Question:
May Allah reward you, Honorable Shaykh (may Allah preserve him). We were traveling and delayed the Maghrib prayer with the women until 'Isha'. When it was time for prayer, I was the imam. I then stood for the prayer with the intention of praying 'Isha, because I had forgotten that I had not prayed Maghrib. When I sat for the tashahhud, I remembered, so I stood up and performed a third rak'ah to make it the Maghrib prayer. When I finished, I stood for the 'Isha prayer and prayed two rak'ahs. What is the ruling on my action, and on the action of those who were praying behind me as ma'mum?

Answer:
This is not valid, because you intended 'Isha, and you do not change the intention to Maghrib while you are in the prayer. You do not change it to Maghrib while you are in the prayer. It was obligatory for you to complete it as a voluntary prayer, and when you finished the prayer, you should have prayed Maghrib first, then prayed 'Isha. Yes, in that order. You must repeat the prayer. Because the jurists say that if one changes his intention from one obligatory prayer to another, it is invalid; both the prayer he changed from and the prayer he changed to are invalid. So this prayer is invalid. Therefore, you must repeat the Maghrib prayer and the 'Isha prayer. Yes.