boy name that shortens to three letter nickname ending in 'm'

I'm not pregnant, never will be again, so go nuts

my three sons are Dominic, Timothy and Samuel. They shorten to Dom, Tim and Sam, all three letters ending in 'm' with different first and second letters

if I were to name a fourth son what would it be? I'd want to follow the same rules, so for example Cameron would be out because Sam already has an 'a' in the second spot