Here are some fem middle names which I think stylistically match up with [name_u]Dylan[/name_u].
[name_u]Dylan[/name_u] [name_f]Celeste[/name_f]
[name_u]Dylan[/name_u] [name_f]Amelia[/name_f]
[name_u]Dylan[/name_u] [name_f]Louisa[/name_f]
[name_u]Dylan[/name_u] [name_f]Georgia[/name_f] - [name_f]My[/name_f] fave.
[name_u]Dylan[/name_u] [name_f]Olivia[/name_f]
[name_u]Dylan[/name_u] [name_f]Katia[/name_f]
[name_u]Dylan[/name_u] [name_u]Juniper[/name_u]
[name_u]Dylan[/name_u] [name_f]Briana[/name_f]