American Dragon Jake Long

Newborn Rose (left) with her unnamed identical twin sister next to her, being held by their mother fourteen years ago.

"Congratulations! They're twins."

During an adventure in the dream realm[1], A suppressed memory/flashback of Rose's infancy revealed not only what her parents had looked like, but that she also has an older twin sister, who's name is unknown.

She is only seen in a flashback/dream in the episode "Dreamscape" as a newborn on the right, being held by her mother. For unknown reasons, she remains unseen in "Homecoming" and the series finale.

Some fans thought of giving another flower name like Rose; either Lily, Daisy or even Violet. Plus, they speculated that she either died, went to boarding school or was taken by the Huntsclan instead of Rose as a result of Jake's wish. It's unclear what truly happened to her.

She and Rose are the second and last set of twins after the Oracle Twins.