Complex sentence: In May 1990, Windham returned to WCW and rejoined the Four Horsemen which at that point consisted of Ric Flair, Arn Anderson, Sid Vicious, and Ole Anderson, who was only semi-active at the time and permanently became their manager once Windham joined.
Split into simpler sentences: In May 1990, Windham joined World Championship Wrestling (WCW) and re-united with the Four Horsemen which at that point consisted of Ric Flair, Arn Anderson, Sid Vicious, and Ole Anderson. At the time, Ole Anderson was only semi-active and permanently became their manager once Windham joined.