I really went down a rabbit hole with this 
You have such a gorgeous list!
girl combos (using your list)
Sylvie Wednesday
Merrily Frances
Birdie Zipporah
Agatha Sylvie “Aggie”
Zelda Garland
Alcott Phoebe
Favor Alice
Fern Beatrix
Clotho Prudence
Cavatica Day
Winsome Ida
Vision Elouise
Alice Chrysanthemum
Imogen Beulah
Royce Winifred “Roycie”
Ruthie Darling “Ruth"
Holiday Agnes
Philomena Bright
Pepper Mildred
Tabitha Favor
Wisteria Eloise
Roberta Violet
Oona Hyacinth
Merit Albertine
Helena Myrtle “Lenny”
Hildegard Louisa “Hilda”
Gwyneth Ramona “Gwen”
May Beverly
Edelweiss Viola “Evie” (or Viola Edelweiss)
Quimby Martha
Louisa Clementine
Concordia June
Bernadette Elm
Pleasance Clara “Percy”
Blythe Harriet
Cordelia Bliss
girl combos (not from your list)
Augusta Patience “Gussie”
Honor Susannah
Edwina Pearl “Winnie”
Leona Bronte
Marjorie Tess “Madge”
Alba Lenore
Eunice Fern
Loretta Opal
Wilhelmine Ada “Minnie”
Marian Cora
Ernestine Daisy
Lois Diana
Polly Christmas
Benedicte Snow
Glenna Dorothy
Lucinda Plum “Lindy / Lucy”
Doris Winter
Georgiana Blair
Elnora Mabel
Thelma Pauline
Greta Florence
Clarice Amelia
boy combos (using your list)
Peregrine Theodore
Gideon Fox
Hawthorne Amos “Hart”
Linus Hummingbird
Otis Murphy “Oatie”
Lemmy Cardinal
Hazel Ambrose
Cassian Elm
Barnaby Hugo
Alistair Felix
Arcturus Perrin “Bear”
Leif Endymion
Morris Valentine “Morrie / Moss”
Sinclair Benedict
Worthy Finnegan
Peter Alcott
Sidney Valentine
Bravery Edward “Brave”
Robin Herschel
Royce Augustine “Roycie”
October Henry “Otto”
Perrin George
Clement Rory
Humphrey Sorrel “Hugh”
Ignatius Plenty
Horatio Gardener
Magnus Wolf
Wilbur Lenny
Basil Harvey “Bash”
Rupert Sycamore “Rueby”
Phineas October
Casper Louis
Merit Oliver
Wynn Balthasar
Earnest Milo
boy combos (not from your list)
Grover Elwood
Curtis Abner
Howard Cypress “Howie”
Cornelius Dove
Frankie Hollis
Misha Frost
Sylvester Ned
Quimby Jack
Dewey Jasper
Willoughby Joy
Florin Shepherd
Wallace Abel “Wally”
Lionel Barry
Rufus Micah
Woody Nathaniel
Clifford Tobias “Kit”
Gilbert Ellis
Gerald August
Ralphie Asa
sibling sets
Sylvie Wednesday, Alice Chrysanthemum, Louisa Clementine, & Peter Alcott
Helena Myrtle, Augusta Patience, & Georgiana Blair
Leona Bronte, Marion Cora, & Casper Louis
Tabitha Favor, Ruthie Darling, & Gwyneth Ramona
Birdie Zipporah, May Beverly, Fern Beatrix, & Otis Murphy
Doris Winter, Polly Christmas, & Robin Herschel
Lucinda Plum, Imogen Beulah, Cordelia Bliss, & Gilbert Ellis
Loretta Opal & Clarice Amelia
Marjorie Tess, Roberta Violet, & Gerald August
Lois Diana & Alba Lenore
Eunice Fern, Thelma Pauline, & Clifford Tobias
Agatha Sylvie & Zelda Garland
Morris Valentine, Sinclair Benedict, & Royce Augustine
Humphrey Sorrel, Wallace Orchard, & Rupert Sycamore “Hugh, Wally, & Rueby”
Sidney Valentine & Elnora Mabel
Greta Florence & Curtis Abner
Gideon Fox & Magnus Wolf
Lionel Barry, Frankie Hollis & Wilbur Lenny
Linus Hummingbird & Oona Hyacinth
Wilhelmine Ada, Hildegard Louisa, & Peregrine Theodore
Bernadette Elm, Edwina Pearl, & Cornelius Dove
Clotho Prudence & Perrin George
Concordia June, Honor Susannah, Phineas October, & Alistair Felix
Cavatica Day, Benedicte Snow, & Arcturus Perrin
Ignatius Plenty, Cassian Elm, & Horatio Gardener
Philomena Bright, Ernestine Daisy, Sylvester Ned, & Willoughby Joy
Pleasance Clara, Worthy Finnegan, & Bravery Edward
Merrily Frances, Favor Alice, Alcott Vision, & Dewey Jasper
Holiday Agnes & Winsome Ida
Pepper Mildred, Glenna Dorothy, & Leif Endymion
Merit Albertine, Blythe Harriet, & Quimby Jack
Wisteria Eloise, Hawthorne Amos, & Edelweiss Viola
Misha Frost, Basil Harvey & Florin Shepherd
Hazel Ambrose & October Henry
Lemmy Cardinal & Grover Elwood