Complex sentence: On December 20,1971, Roy Disney died of a stroke, leaving the company under control of Donn Tatum, Card Walker, and Walt's son-in-law Ron Miller, each trained by Walt and Roy.
Split into simpler sentences: On December 20,1971, Roy Disney died of a stroke. He left the company under control of Donn Tatum, Card Walker, and Walt's son-in-law Ron Miller, each trained by Walt and Roy.