Complex sentence: Reshma threatens to kill Pooja if Roop won't stop fighting with his brother, and when he stops, Ajay tries to kill Roop and Pooja but misses and hits Reshma instead.
Split into simpler sentences: Reshma threatens to kill Pooja if Roop won't stop fighting with his brother. When he stops, Ajay tries to shoot Roop and Pooja, but misses and hits Reshma instead.