Она только что получила письмо от б

Она только что получила письмо от брата, который вернулся с севера, где он пробыл долгое время

Результаты (английский) 1:

She had just received a letter from my brother, who returned from the North, where he stayed for a long time

Результаты (английский) 2:

She had just received a letter from his brother, who had returned from the north, where he stayed for a long time

Результаты (английский) 3:

she just received a letter from my brother, who came from the north, where he remained for a long time.