I like to follow the names coming in and out of style and while I love traditional names, I`m thinking Peter and Autumn will go with something a little less traditional than Anne or Elizabeth. Autumn is not a traditional name, neither is Zara for that matter. I`m guessing they`ll choose a semi-traditional name that is popular without being extremely trendy. Autumn is Canadian, so maybe they`ll choose one of the names that are popular in both the UK and Canada right now.
Some examples: Olivia, Ruby, Grace, Chloe, Isabella, Abigail, Sophia, Lily, Emma--all really common in both the UK and Canada. For boys: Daniel, Ethan, Alexander, Benjamin, Max, Thomas, Adam.
I think there will either be one or two middle names and they will probably be family names. For boys, Mark, Bryan or maybe Christopher after Autumn`s twin brother; for girls, Anne or Elizabeth or Patricia. I`m definitely betting on Elizabeth as a middle name, actually, just because so many people I know have Elizabeth as a middle name anyway, without the Queen being their great-grandmother.
Okay, I`ll make up a few names for guesses:
Benjamin Mark Peter
Adam Mark Christopher
Grace Elizabeth Patricia
Ruby Anne Elizabeth
I was going for Anne Patricia as a middle name combo for one of those names, but since that gives me the initials G.A.P. and R.A.P., I thought better of it.