This is way premature as I'm still early in the first trimester
but as we've told No People IRL about this pregnancy (two m/c in between DC1 and DC2) I have to Go Mad on the Internet...
So, sibling for a Jack and a Margot?
Boys:
William
Henry (too popular? as the thread says below?)
Edward
Girls:
Sophie
Imogen
Emilia
Or any other ideas!