What is the ruling on praying 'Isha first with the intention of 'Isha, then making up Maghrib second, and is this permissible according to the four madhhabs, especially according to the madhhab of Imam Malik?

Fatwas no. 30292 and 33300 do not align with the Maliki school of thought. The Malikis stipulate for the validity of following an Imam that the prayer of the follower must be the same as the prayer of the Imam, and that they must be equal in performance (adaa') and make-up (qadaa'). Therefore, according to them, praying Maghrib behind someone praying Isha is not valid. Also, according to them, there must be an order between the two present prayers that share a common time, provided one remembers, so it is not permissible to pray Isha before Maghrib. If someone misses Maghrib and the Isha prayer is being established, they should pray Maghrib first, then join the Isha congregation if possible, or pray individually.