At Carlo and Connie's wedding -
[This is also introducing the various characters to us the audience as well]

• Tom and Michael embrace
• Michael makes the introduction “My brother, Tom Hagen This is Kay Adams”
• Michael only offers further information after Kay asked “If he's your brother, why does he have a different name?”
• Michael goes on “Oh, ah, that -- when my brother Sonny was a kid, he found Tom Hagen in the street and he had no home so my father took him in and he's been with us ever since”
  It came across to me as a feel-good story, showing Michael's family benevolent helping the less fortunate, homeless Street kid [not even a Sicilian!] without any strings attached
• Michael goes on “He's a good lawyer not a Sicilian but I think he's gonna be consiglieri”
• Then Michael explains further after Kay asked “What's that?” "That's like a counsellor an advisor very important to the family”
  seemed to me with pride that even though Tom is not a Sicilian he is family and very important member

Besides at this time, the Corleones were flying high
Vito had not been shot, Sonny was alive, Carlo had not shown his true colours Only Happiness and Peace

So among others even ifThese were events down the track so really had no bearing on the wedding talk