[2] Related characters have been introduced in the parks, expanding into a merchandise line called "Duffy and Friends", which includes ShellieMay, Gelatoni, StellaLou, CookieAnn, 'Olu Mel and LinaBell.

[2] The Oriental Land Company aggressively marketed Duffy in the Tokyo DisneySea park, and he was added as a walk-around character in 2005.

[2] Capitalizing on Duffy's success at Tokyo DisneySea, the park began introducing new characters.

On January 22, 2010, a female bear named ShellieMay debuted in the park as Duffy's friend.

[9] On September 29, 2021, LinaBell the fox was introduced in Shanghai, as part of the park's 5th anniversary celebrations.

[12] On June 30, 2020, the Disney Parks posted on YouTube a stop motion short called "Morning Glories" featuring Duffy and Friends.