According to the Novel, Michael's first two children were boys.
This means Mary Corleone never existed. Since GFIII revolves around her, lets just make it all a dream from which Michael awakens at the end of GFII, and remake GFIII with Michael becoming an old man and becoming legitimate.
"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."
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