Complex sentence: Donors contribute in many ways to the shelter, including providing items the cats need, donating money, or attending fundraisers, which Siglinda holds often with such recent themes as Burrito Bash, Venetian Carnival, Garden Gourmands, and Mad Hatter's Tea Party.
Split into simpler sentences: Donors contribute in many ways to the shelter, including providing items the cats need, donating money, or attending fundraisers. Siglinda; s fundraisers use themes such as Burrito Bash, Venetian Carnival, Garden Gourmands, and Mad Hatter's Tea Party.