Complex sentence: Madhav Sharma and Indira Joshi will make their first appearances in January as Arshad Ahmed and Mariam Ahmed, the uncle and aunt of Masood Ahmed (Nitin Ganatra).
Split into simpler sentences: Madhav Sharma and Indira Joshi will make their first appearances in early 2018 as Masood Ahmed's (Nitin Ganatra) uncle and aunt, Arshad and Mariam Ahmed. Arshad is the uncle of established character Masood Ahmed (Nitin Ganatra).