I'd use Theodore "Theo", but I know someone who has a son named Matteo "Teo" too.
From your suggestions I prefer Theodore (it's one of my absolute favorites) but I think that Edward sounds best with Amy and Thomas. Or Vincent.
Let us step into the night and pursue that flighty temptress, adventure.
PNL: http://www.behindthename.com/pnl/45898
Top: Alice and William
Bottom: Kenzie and Alvin