But wouldn't Jade and Rose be cousins in some way. Seeing as Jade is Grandpa Harley's granddaughter, Mom Lalonde would be her Aunt (being Grandpa's daughter) via adoption. Or Jade and Mom Lalonde would be seen as siblings via adoption and Jade's biology and being raised by the same person. Making Jade Rose's Aunt.

Seeing Jade as Grandpa’s granddaughter would make her Rose’s cousin, but viewing her as Grandpa’s daughter would make her Rose’s aunt. Both views are correct.