Fredo didn't have a clue. He thought Michael forgave him at their mother's funeral.
As for Connie, my guess is she figured it out right away but ket her mouth shut. After all if Anthony figured it out, COnnie would have.
"Io sono stanco, sono imbigliato, and I wan't everyone here to know, there ain't gonna be no trouble from me..Don Corleone..Cicc' a port!"
"I stood in the courtroom like a fool."
"I am Constanza: Lord of the idiots."
| 
