Complex sentence: Reasons for doing so may concern upon the fact Andrew Mears, rhythm guitarist and lead vocalist of Youthmovies, was once a member of Foals previous to when Edwin Congreave the current keyboardist had joined.
Split into simpler sentences: Reasons for doing so may concern upon the fact Andrew Mears'Rhythm guitarist and lead vocalist' of Youthmovies was once a member of Foals. Previous to when Edwin Congreave the current keyboardist had joined.