Complex sentence: Petersen managed Jonathan Kelly as a solo artist during the early' 70s subsequent to Humpy Bong disbanding and returned to Australia in 1974 where, having lost his rights to royalties after his court case against the Bee Gees, eventually became a painter residing in Sydney.
Split into simpler sentences: Petersen managed Jonathan Kelly as a solo artist during the early 1970s, subsequent to Humpy Bong disbanding. He returned to Australia in 1974 where, having lost his rights to royalties after his court case against the Bee Gees, eventually became a painter residing in Sydney.