Nora, Amber, Elise, Febe (really super, doesn't really fit with Fay), Tara or Lara

Personally, I don't really care if the names go well together—I didn't take that into account with my own kids either. After all, each child is their own unique person, right? But of course, everyone has their own preferences.

I think Nikki and Fay go well together, or Fay and Liz. Fay and Sanne also work. Fay and Lynn, or Fay and Tes or Fay and Tessa These are the girl names that come to mind for me as good matches for Fay.

Hope you find something that works for you!

I think they're all beautiful names, Tara and Amber a bit less so than the rest. Good luck!

Fay and Febe: then you might shorten Febe to Fee, and then you'd have 2 daughters with the same nickname? I wouldn't do that. Besides, I associate Febe with Febo.
Nora: nice
Amber: nice
Elise: classic, also quite ordinary
Tara or Lara: association with busty bimbos

I think Febe is really beautiful, but indeed too much with Fay. Maybe nice as a second name, a reference to her sister!
Amber and Elise I find nice timeless names.
Nora, Tara and Lara I find very beautiful, also in combination with Fay.
The most beautiful I find Fay and Lara. And then fully maybe Lara Febe.

Thanks for the replies. Febe as a second name is indeed an idea???? I have a slight preference for Amber or Nora, but I still don't feel like it's THE name... sigh... it's tricky though..