Thanks for all the replies.

I think like a few people have said the more you say the names the more they will just "go together".

We really like the name Evie for a girl atm and I think that is why I am sceptical, cause it is the opposite extreme of the other two! But the more I repeat them, Gabriella, ALexander and Evie, or Gaby, Alex and Evie they sound ok!

Still would love to hear more opinions on siblings names tho!