Aidan misspelled and used for a girl are both no-no's in my book. Sorry. Especially paired with such a pretty, feminine name like
Nadia. Everyone will assume they are brother & sister upon first hearing the names. I say stick with
Nadia, and if you must, use
Aidan or a variant as the mn for a little girl. Even b/g twins named
Aidan &
Nadia would be better than sisters named
Nadia & Aydan imo.
~
Heather~
