How can one combine prayers (whether by advancing them or delaying them) with shortening them, when a Muslim returns home from work, and the Adhan for Maghrib overtakes him while he is on the way, and then the Adhan for Isha also overtakes him while he is still on the way?

You are permitted to combine the Maghrib and Isha prayers and shorten the Isha prayer if the distance between your work and home is approximately 85 km, provided that you pray before reaching your home. However, if you arrive home after the time for Isha has begun, you should first pray Maghrib, then Isha with four rak'ahs. If you usually pray before the time for Isha begins, then you must perform each prayer fully within its designated time, because the condition for the continuation of the excuse (travel) will cease. If the distance is less than 85 km, you are not permitted to combine and shorten the prayers; instead, you must perform each prayer at its designated time. If that is difficult, there is no harm in intending to combine prayers out of necessity, but do not make this a habit, based on the hadith (definition) of Ibn Abbas: "He (the Prophet) intended not to burden his Ummah."