This is a wonderful & eclectic list! Some ideas inspired by yours…
[name_f]Althea[/name_f] → [name_u]Alma[/name_u], [name_u]Alva[/name_u], [name_f]Annora[/name_f], [name_f]Calla[/name_f], [name_f]Joanna[/name_f], [name_f]Theodora[/name_f]
[name_f]Autumn[/name_f] → [name_u]Auden[/name_u], [name_f]April[/name_f], [name_f]Avalon[/name_f], [name_u]Ember[/name_u], [name_f]Summer[/name_f], [name_u]Winter[/name_u]
[name_f]Dulcie[/name_f] → [name_f]Betsy[/name_f], [name_u]Darcy[/name_u], [name_f]Dolly[/name_f], [name_f]Dottie[/name_f], [name_f]Elsie[/name_f], [name_f]Sally[/name_f]
[name_f]Elin[/name_f] → [name_u]Dagny[/name_u], [name_u]Eden[/name_u], [name_f]Enid[/name_f], [name_f]Freya[/name_f], [name_f]Leni[/name_f], [name_f]Linnea[/name_f], [name_u]Malin[/name_u], [name_f]Signy[/name_f]
[name_f]Elowen[/name_f] → [name_f]Cerys[/name_f], [name_f]Elodie[/name_f], [name_u]Linden[/name_u], [name_f]Lyra[/name_f], [name_f]Guinevere[/name_f], [name_f]Winnie[/name_f]
[name_f]Iona[/name_f] → [name_f]Diana[/name_f], [name_f]Ida[/name_f], [name_f]Isla[/name_f], [name_f]Irina[/name_f], [name_f]Orla[/name_f], [name_f]Oona[/name_f], [name_f]Ramona[/name_f], [name_f]Simona[/name_f]
[name_f]Lilia[/name_f] → [name_f]Celia[/name_f], [name_f]Lelia[/name_f], [name_f]Leora[/name_f], [name_f]Liana[/name_f], [name_f]Livia[/name_f], [name_f]Millie[/name_f], [name_f]Vivia[/name_f]
[name_f]Lucia[/name_f] → [name_f]Celina[/name_f], [name_f]Chiara[/name_f], [name_f]Julia[/name_f], [name_f]Lenora[/name_f], [name_f]Lucinda[/name_f], [name_f]Malia[/name_f]
[name_f]Maeva[/name_f] → [name_f]Elara[/name_f], [name_f]Elva[/name_f], [name_f]Leia[/name_f], [name_f]Nella[/name_f], [name_f]Veda[/name_f]
[name_f]Maelie[/name_f] → [name_u]Arlie[/name_u], [name_f]Hallie[/name_f], [name_f]Kaylie[/name_f], [name_f]Mabli[/name_f], [name_f]Orly[/name_f], [name_f]Sadie[/name_f], [name_f]Tenley[/name_f]
[name_f]Merryn[/name_f] → [name_u]Larkin[/name_u], [name_f]Maren[/name_f], [name_u]Meredith[/name_u], [name_u]Mirren[/name_u], [name_u]Perrin[/name_u], [name_u]Sierra[/name_u]
[name_u]Marlowe[/name_u] → [name_u]Arden[/name_u], [name_u]Harlow[/name_u], [name_u]Indigo[/name_u], [name_f]Margot[/name_f], [name_u]Romy[/name_u], [name_u]Winslow[/name_u]