Isabelle got most of her Isabelle-ness from the dolls that follow her in the picture. It is the line with Isabelle, McKenna, Lanie and Mia. Same with Saige's line.
Isabelle got her hair from McKenna, but the color from Lanie. She got hair kit and eyes from Mia.
Saige got her long hair from Kanani and her picnic set from Chrissa. She got her freckles from Nicki.
See what I mean? There is always a pattern with these GOTY dolls following every other doll.