Mr Wittstock died while paragliding on April 13, and event organiser Marissa Natale said the May 24 family fun day would support his fiance and daughter.
"Kyle was a 22-year-old apprentice electrician due to finish his apprenticeship this month and he was taken from us way too soon," she said.
"His fiance Kelley (Romanelli) had given birth to their daughter Kiara only two months prior to the accident.
"All funds raised will be going directly to Kelley and Kiara to help them make it through this tough time."
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READ NOWThe fundraiser at The Locals juice bar on Stevenage Street, Yanchep will include haircuts for donations, coloured hairspray for children, a 5km run with coloured balloons, lolly stall, sausage sizzle and auction of donated products, services and vouchers.
Businesses wishing to donate other auction items or entertainment services can email marissa.natale@gmail.com.
The fundraiser will run from 9am to 4pm. For more, visit facebook.com/events/ 554353804704314/