Rosallion is out of Rosaline (New Approach), who never raced, and is her fourth foal and second winner. Rosaline is a full sister to Ostilio, winner of the Gr.2 Prix Daniel Wildenstein.

Second dam Reem Three (Mark of Esteem) won three times and was placed in the Hoppings Stakes, then a Listed race. She has ten winners, six of them black-type winners, headed by Triple Time (Frankel), winner of the Gr.1 Queen Anne Stakes and now a sire. She is also the dam of Ajman Princess (Teofilo), winner of the Gr.1 Prix Jean Romanet, whose son Inisherin won the Gr.2 Sandy Lane Stakes, of Ostilio, of the Group 3 winner Cape Byron (Shamardal), the dual Listed winner Third Realm (Sea The Stars), the Listed winner Captain Winters (Lope De Vega) and the Group 1-placed Imperial Charm (Dubawi).

Third dam Jumaireyah (Fairy King) won twice and had five other winners, the best of them Afsare (Dubawi), winner of the Gr.2 Celebration Mile.

Rosaline has an unraced two-year-old colt by Make Believe named Lord Capulet and visited Dubawi in 2023.