Bonjour! Looking for a name for a strong-willed girl with two younger brothers.
Her brothers names are:
[name_m]Tristian[/name_m] [name_m]Xavier[/name_m] [name_u]James[/name_u]
[name_m]Felix[/name_m] [name_u]Alfie[/name_u] [name_u]James[/name_u]
Names I like:
[name_u]Ruby[/name_u]
[name_u]Blue[/name_u]
[name_f]Gemma[/name_f]
[name_f]Agatha[/name_f]
[name_f]Cordelia[/name_f]
[name_f]Esther[/name_f]
[name_f]Imogen[/name_f]
[name_f]Emilia[/name_f]
[name_f]Althea[/name_f]
From your list, I like [name_f]Gemma[/name_f] and [name_f]Imogen[/name_f]. I also think [name_f]Britta[/name_f] and [name_f]Sadie[/name_f] might work for your story. Did you want full names? Good luck on your writing !!
From your list I think [name_u]Ruby[/name_u] [name_f]Gemma[/name_f] and [name_f]Imogen[/name_f] would work well. I love the name [name_f]Emilia[/name_f] but I don’t picture a strong-willed girl. Other names:
[name_f]Emily[/name_f]
[name_u]Taylor[/name_u]
[name_f]Jasmine[/name_f]
[name_f]Sadie[/name_f]
[name_f]Savannah[/name_f]
[name_f]Emma[/name_f]
[name_u]Hadley[/name_u]
[name_f]Georgia[/name_f]
[name_f]Alice[/name_f]
[name_u]Ali[/name_u] (full names: [name_f]Alison[/name_f], [name_f]Alicia[/name_f], [name_f]Alyssa[/name_f])
[name_f]Alexandra[/name_f]
[name_f]Claire[/name_f]
[name_f]Kate[/name_f]
[name_f]Zoe[/name_f]
[name_f]Laura[/name_f]
[name_f]Maddi[/name_f] (full name [name_u]Madison[/name_u])
[name_f]Ebony[/name_f]
[name_f]Elodie[/name_f]
[name_f]Hope[/name_f] this helps! 
Good luck writing your story
What do you think of [name_f]Esther[/name_f] [name_f]Athena[/name_f]? Here is a list of what I like:
[name_f]Lily[/name_f]
[name_f]Athena[/name_f]
[name_f]Esther[/name_f]
[name_f]Rose[/name_f]
[name_u]Ruby[/name_u]
[name_f]Fiona[/name_f]
[name_f]Flora[/name_f]
[name_f]Elodie[/name_f]
[name_u]Eloise[/name_u]
[name_f]Elsie[/name_f]
[name_f]Georgia[/name_f]
[name_f]Joy[/name_f]
[name_u]Joyce[/name_u]
[name_f]Lucy[/name_f]
[name_f]Lucia[/name_f]
[name_f]Lucille[/name_f]
[name_f]Kendra[/name_f]
I also like [name_f]Athena[/name_f] [name_f]Rose[/name_f] [name_u]James[/name_u].
From your list I think I’d go with [name_u]Ruby[/name_u] [name_f]Gemma[/name_f] - to me at least, the other names sound a little too feminine.