This is the novel rather than the movie, so there’s a lot more to play with. The sequel, Scarlett, never existed and as such no character unique to it may be included, though characters referenced in GWTW but not actually portrayed (such as Ellen’s cousin/lover Philippe, for example) can be included.
We’ll do one at a time, but I am gonna start off with Scarlett’s immediate family at the beginning:
Will Benteen, the Cracker they rescued who would’ve married Carreen had she been willing (but settled for Suellen instead).
Suellen’s daughter, Little Sue, whom Bonnie bit
Melanie and Ashley’s son, little Beau
Scarlett’s other kids, Wade Hampton Hamilton and Lorena (sp? might have the wrong contraction)
Uncle Henry Hamilton, Miss Pittypat’s lawyer brother
Mrs. Meade, town dowager
Mrs. Elsing, same
Hugh Elsing, her son
Fanny Elsing, her daughter
Dr. and Mrs. Merriweather
Big Sam, the foreman of Tara who saved Scarlett from being raped
Dilcey, the wife of Pork, Gerald’s butler, who nursed both her child and little Beau
Dilcey’s first child, Prissy (?) who didn’t know nuthin’ about birthin’ babies
Mrs. Tarleton, Beatrice, who had quite a few kids - Randi, little Betsy, two more girls whose names escape me, Boyd and Tom (in addition to the twins).
Jonas Wilkerson, the Yankee Overseer
The White Trash Slattery Girl, his wife
Maybelle Merriweather
Her Zouave boyfriend (who had a name in the book…in the movie, he’s just the one who says “$20!! $20 for Maybelle Merreeeweathaar!”)