What happens when winning against your sister could mean $50,000 for your favorite charity? Sibling rivalry has never been this much fun as Charli and Dixie put their best fashion forward in this, the first in a series of exciting challenges for the social media stars

Charli and Dixie compete head-to-head in the "Transformation" challenge

Charli and Dixie compete in perfecting cake making.

With the help of Rachel Taylor, Charli and Dixie destroy tiny houses.

Charli, Dixie, Heidi, and Marc participate in a family name night.

Charli and Dixie get tattoos.