Not sure I'm with you here: you like
Sam names. You can't call a possible son
Sam because of his aunt. So you give him a
Sam name and call him by the non-Sam segment. Right?
Well, not really.
Sonny can be used for any male child from
Adam to
Zachariah. And when he's old enough, he'll want to drop it - which presumably will mean becoming either
Samson or
Sam!
In your place (which I wouldn't be because I really dislike
Sam names for both genders), I'd use any
Sam name that sounded good as a mn. Like keeping some brooch or lace collar you'll never use at the back of a drawer for ever because it's so beautiful, but you only see it once a year during cleaning spasms.