I think you could pair up any of your choices to be honest - they all work well together.
I think Ivy and Violet are fine together and really like Finn and Milo as a pair.
Astrid and ...
Romilly, Saffron, Honor, India, Juliet, Tamara
Felix, Robin, Harley, Jesse, Xaver
Matilda and ...
Abigail, Arabella, Charlotte, Felicity, Rebecca, Sophia, Georgina
Alexander, Nicholas, Patrick, Joshua, Joseph, Gabriel
Mischa and ...
Alexis, Sasha, Danika, Anoushka, Erica, Ingrid
Artem, Bruno, Rory, Solomon, Raphael
Lyra and ...
Erin, Seren, Delphi, Elise, Bronte, Zara, Posy, Nadia, Cleo, Verity
Arlo, Christian, Ezra, Phineas, Rafi, Monty, Reuben, Zach