Complex sentence: Harriet was diagnosed with cancer and passed away in 2005 at the age of 52, and the Harriet Knor Foundation for Cancer Research was established in her honour shortly thereafter through the efforts of her daughter Leah Knor, and life-long friend Kristy MacDonald.
Split into simpler sentences: Harriet was diagnosed with cancer, passing away in 2005 at the age of 52. The Harriet Knor Foundation for Cancer Research was established in her honour shortly thereafter through the efforts of her daughter Leah Knor, and life-long friend Kristy MacDonald.