Liv is my favourite 
I like Liv Natalia!
Some other middle name ideas:
Liv Cressida
Liv Betsabe
Liv Wilhelmina
Liv Bernadette
Liv Antonia
Liv Arianell
Liv Solja
Liv Celandine
Liv Ottilia
Liv Christabel
Liv Cariadwen
Liv Nadia
Liv Briony
Liv Damaris
And some for Olivia and Livia, just because:
Livia Sigrid
Livia Kinneret
Livia Pernille
Livia Solange
Livia Tessel
Livia Shoshana
Olivia Ingvild
Olivia Hagar
Olivia Yael
Olivia Vashti
Olivia Muriel
Olivia Pomeline
Olivia Dodie
Olivia Aamu