Complex sentence: Over 1,000 people attended a demonstration near the site, the "Jam for the Dam" march and music event was organised in Manly (attended by over 4,000 people) there were also rallies at NSW parliament and Warringah Council.
Split into simpler sentences: Over 1,000 people attended a demonstration near the site, the "Jam for the Dam" march and music event was organised in Manly, attended by over 4,000 people. There were also rallies at NSW parliament and Warringah Council.