Sibling for [name_f]Heidi[/name_f]? Leaning towards [name_f]Annie[/name_f] or [name_f]Ally[/name_f] (Allison). I also like [name_u]Brooke[/name_u] and [name_u]Halle[/name_u] (but think [name_u]Halle[/name_u] is too similar). We have a single syllable last name so hoping for a two syllable first with a y or I or ie sound at the end like [name_f]Heidi[/name_f].
Thoughts?!
[name_f]Heidi[/name_f] and [name_f]Annie[/name_f] are an adorable pair!
Other ideas ~
[name_f]Sylvie[/name_f]
[name_f]Sophie[/name_f]
[name_f]Rosie[/name_f]
[name_f]Posie[/name_f], [name_f]Poesy[/name_f]
[name_f]Maisie[/name_f]
[name_f]Tillie[/name_f]
[name_f]Tessa[/name_f]
[name_f]Thisbe[/name_f]
[name_f]Daphne[/name_f]
[name_f]Bella[/name_f]
[name_f]Winnie[/name_f]
[name_f]Poppy[/name_f]
[name_f]Effie[/name_f]
[name_u]Kitty[/name_u]
[name_f]Lottie[/name_f]
[name_u]Georgie[/name_u], [name_f]Gigi[/name_f]
[name_f]Dottie[/name_f], [name_f]Dodie[/name_f]
[name_f]Sadie[/name_f]
[name_f]Lizzy[/name_f], [name_f]Lizzie[/name_f], [name_f]Lissy[/name_f]
[name_f]Elsie[/name_f]
[name_f]Millie[/name_f]
[name_f]Clara[/name_f]
[name_f]Jilly[/name_f]
Saffy
[name_f]Eppie[/name_f]
[name_u]Mattie[/name_u]
[name_f]Polly[/name_f]
[name_f]Molly[/name_f]
[name_f]Emmy[/name_f]
[name_f]Heidi[/name_f] and [name_u]Halle[/name_u] is lovely, other suggestions…
[name_f]Heidi[/name_f] and…
[name_u]Connie[/name_u]
[name_f]Ginnie[/name_f]
Eadie/Edie
[name_u]Emery[/name_u]
[name_u]Avery[/name_u]
[name_u]Billie[/name_u]
[name_f]Libbie[/name_f]
[name_f]Hettie[/name_f]
[name_u]Holly[/name_u]
[name_f]Molly[/name_f]
[name_f]Ottilie[/name_f]
[name_f]Eleni[/name_f]
[name_f]Elodie[/name_f]
[name_f]Adelie[/name_f]
[name_f]Nettie[/name_f]
[name_f]Nixie[/name_f]
[name_f]Andie[/name_f]
[name_f]Rosie[/name_f]
[name_f]Mitzi[/name_f]
[name_f]Katie[/name_f]
[name_u]Kitty[/name_u]
[name_u]Marley[/name_u]
Lyssi
[name_f]Lydie[/name_f]
[name_f]Sylvie[/name_f]
Amory/Amori
[name_f]Leonie[/name_f]
[name_f]Cecily[/name_f]
[name_f]Franzi[/name_f]
[name_u]Fritzi[/name_u]
[name_u]Josie[/name_u]
[name_u]Jodie[/name_u]
[name_f]Evie[/name_f]
[name_f]Elsie[/name_f]
[name_f]Betty[/name_f]
Carrie/Karrie
[name_f]Luzie[/name_f]
[name_f]Aggie[/name_f]
[name_u]Bobbie[/name_u]
How about…
[name_f]Elsie[/name_f], [name_f]Jolie[/name_f], [name_u]Hazel[/name_u], [name_f]Leila[/name_f], [name_f]Siena[/name_f], [name_u]Eden[/name_u], [name_f]Poppy[/name_f], [name_u]Marley[/name_u], [name_f]Olive[/name_f], [name_f]Bonnie[/name_f], [name_f]Vera[/name_f], [name_f]Sophie[/name_f], [name_f]Wendy[/name_f], [name_f]Alice[/name_f], [name_u]Piper[/name_u], [name_u]Josie[/name_u], [name_f]April[/name_f] or [name_f]Sadie[/name_f]?
Annie is seriously perfect with Heidi !! 
You might also like:
Cleo
Daisy
Elsie
Esme
Eloise
Elodie
Frankie
Felicity
Greta
Iris
Kaia
Louisa
Lola
Lara
Lainey
Laurel
Maisie
Molly
Marley
Noelle
Olive
Phoebe
Penny
Pippa
Poppy
Rosalie
Rosie
Sylvie
Tessa
Thea
Thalia
Vera
[name_f]Heidi[/name_f] and [name_u]Allison[/name_u] ‘Ally’ are great!!!
[name_u]Brooke[/name_u] is also pretty!
What about…
[name_f]Sylvie[/name_f]
[name_f]Emily[/name_f]
[name_u]Kitty[/name_u], [name_f]Kittie[/name_f]
[name_f]Amy[/name_f], [name_f]Aimee[/name_f]
[name_f]Lucy[/name_f], [name_f]Lucie[/name_f]
[name_f]Lily[/name_f]
[name_u]Ivy[/name_u]
[name_f]Ellie[/name_f]
[name_f]Molly[/name_f]
Heidi & ________:
Maren
Johanna
Marnie
Frances/Francesca
Daphne
Imogene “Ginny”
Ramona
Raquel
Tabitha
Lorelei
Talia
Leona
Ayla
Ruby
Vera
Felicity
Cassidy
Bonnie
Audrey
Estelle
Beatrice
Lydia
Delia
Polly/Molly
Bridget “Birdie”
Penny
Shelby
Maxine
Betsy
Naomi/Noemi
Emmeline “Emmy”
Caroline “Carly”
Nadine
Blair/Claire
Paige
Firstly [name_f]Heidi[/name_f] is gorgeous 
I like [name_f]Annie[/name_f] from your selection of names. [name_f]Annie[/name_f] is adorable and has that cuddly autumnal vibe [name_f]Heidi[/name_f] has. Absolutely stunning!
You’ve had lots of lovely suggestions so count any repeats as me being in agreement with the berries
[name_f]Heidi[/name_f] and…
[name_f]Alice[/name_f] ~ I think she works better than Allie/Allison but has a similar sound
[name_f]Effie[/name_f]
[name_f]Blythe[/name_f]
[name_f]Verity[/name_f]
[name_f]Lena[/name_f]
Callie/Calla~ similar to [name_u]Halle[/name_u] but very distinctive from [name_f]Heidi[/name_f]
[name_f]Pearl[/name_f]
[name_u]Fern[/name_u]
[name_f]Willa[/name_f]
[name_f]Sylvie[/name_f]
[name_f]Olive[/name_f]
[name_u]June[/name_u]
[name_u]Alma[/name_u]
[name_f]Daisy[/name_f]
[name_f]Cora[/name_f]
[name_f]Lilia[/name_f]
[name_u]Robin[/name_u]
[name_f]Hope[/name_f] this helps
I think that [name_f]Heidi[/name_f] and [name_u]Allison[/name_u] “Ally/Allie” work very well together!
I love [name_f]Annie[/name_f] from your list! That’s lovely. [name_u]Anne[/name_u] nn [name_f]Annie[/name_f] would also be beautiful. 
More ideas…
[name_f]Greta[/name_f] (I really love this with [name_f]Heidi[/name_f] for some reason!)
[name_f]Mabel[/name_f]
[name_f]Maisie[/name_f]
[name_f]Elodie[/name_f]
[name_u]Flannery[/name_u]
[name_f]Maud[/name_f] or [name_f]Maudie[/name_f]
[name_f]Winnie[/name_f]
[name_f]Zelda[/name_f]
[name_f]Beatrice[/name_f]
[name_f]Millie[/name_f]
[name_f]Wendy[/name_f]
[name_f]Annie[/name_f] is lovely with Heidi!!
[name_f]Heidi[/name_f] and…
[name_f]Mabli[/name_f]
[name_f]Callie[/name_f]
[name_f]Betsy[/name_f]
[name_u]Ruby[/name_u]
[name_u]Esme[/name_u]
[name_u]Romy[/name_u]
[name_f]Lucy[/name_f]
[name_u]Aubrey[/name_u]
[name_f]Trixie[/name_f]
[name_f]Elsie[/name_f]
[name_u]Tally[/name_u]
[name_f]Gracie[/name_f]
[name_f]Poppy[/name_f]
[name_u]Zoe[/name_u]
[name_f]Phoebe[/name_f]
[name_f]Tilly[/name_f]
[name_f]Lorelei[/name_f]
[name_f]Audrey[/name_f]
[name_f]Lumi[/name_f]
Aylie
[name_f]Bessie[/name_f] / [name_f]Betty[/name_f]
[name_f]Lizzie[/name_f]
[name_f]Marcie[/name_f]
[name_f]Lottie[/name_f]
[name_f]Mari[/name_f]
[name_f]Suzie[/name_f]
[name_u]Josie[/name_u]
[name_f]Ruthie[/name_f]
[name_u]Darcey[/name_u]
[name_u]Laney[/name_u]
[name_u]Ruby[/name_u]
[name_f]Dulcie[/name_f]
[name_f]Nancy[/name_f]
[name_u]Georgie[/name_u]
[name_f]Juni[/name_f]
[name_f]Maggie[/name_f]
[name_u]Dory[/name_u]
[name_f]Jolie[/name_f]
[name_u]Indie[/name_u]
[name_u]Izzy[/name_u]
[name_f]Lacey[/name_f]
[name_f]Trudy[/name_f]
[name_f]Janey[/name_f]
[name_f]Maddie[/name_f]
[name_u]Neely[/name_u]
[name_f]Suki[/name_f]
[name_f]Tansy[/name_f]
[name_f]Addy[/name_f]
[name_f]Emme[/name_f]
[name_u]Remi[/name_u]
[name_f]Dotty[/name_f]
[name_f]Roxi[/name_f]
[name_u]Angie[/name_u]
[name_f]Jeanie[/name_f]
[name_f]Carrie[/name_f]
[name_f]Demi[/name_f]
[name_f]Lumi[/name_f]
[name_u]Kelly[/name_u]
[name_u]Jackie[/name_u]
[name_f]Nellie[/name_f]
[name_f]Zadie[/name_f]