Complex sentence: Harry Vanda was a bandmate of George's in The Easybeats and the pair were the main songwriters of The Easybeats later hits, including their international hit "Friday on My Mind".
Split into simpler sentences: Harry Vanda was a bandmate of George's in The Easybeats. George and Harry were the main songwriters of The Easybeats' later hits, including their international hit "Friday on My Mind".