Coloured them and added Mary whom is their youngest sibling. They were all created as teens...except Mary.

Edit: Old fancomic with them is found here:

Katie
Created by Dr Finklestein as a favour for Jack and Sally. Resembling her mother immensely, she is the second created after Kye (who lives away from Halloween Town presently) and by far the sweetest. She tries constantly to befriend Emily, and sometimes teases Jonathan for being older than him.
Created by *JackAndSally4Ever.

Emily
Dr Finklestein lost to Oogie Boogie during an illegal gambling party and gave up some of his spare parts. Oogie constructed the living voodoo doll from the spare parts and inevitably abandoned her. Emily was found by Sally in the Pumpkin Patch alone, and since then has been adopted into the Skellington family. She has "abandonment issues" and never considered Jack and Sally as her parents. She uses her voodoo abilities to harm others.
Created by *Lily-pily.

Jonathan
The third sibling created by Dr Finklestein, Jonathan has an inferiority complex when it comes to age and his being expected to follow his father in his footsteps, since Kye, the eldest brother, has abandoned his duties as future King. He and Emily don't get along at all, although deep inside he does care for his somewhat estranged sister. Jonathan, on good terms with the Boogie Boys, has an unexplainable crush on Shock, who has since transformed into a bodacious Witchling.
Created by *JackAndSally4Ever

Morgan
The second youngest sibling, Morgan has been somewhat babied during her short life and has a strange fetish for shiny, bright nicknacks. She likes to explore the vast expanses of the Halloween World and thinks Emily is a bit frightening, although, like Katie, tries to make friends with her.
Created by *cheese-grater

Mary
The last to be created by Dr Finklestein, Mary had not developed the same characteristics as her intended siblings and Finklestein considered her a failed experiment due to her undeveloped disfigurement. However, his wife, Jewel took the opportunity to adopt Mary much to Finklestein's dismay.
Belongs to *Neverland-syndrome

Kye
As the oldest son and heir to the Pumpkin throne, Kye was expected to be all his father was and more. However, when he was exposed to the towns traditions he grew to fear all that was Halloween. When he had matured enough, he took the chance to make the hinterlands his new home, away from all that terrified him. Although at this cost had grown considerably distant from his family.
Created by *justawishfulthinker