I have noticed something analogous in the trilogy. At the beginning of these films there are always a grand party and songs and children.
These arrangements may have their hidden meaning. The grand parties and songs build a peaceful and happy aura. And the children are the symbols of innocence. However, all these are not true. Undercurrents of crime and treachery lay behind the disguise.
This is my opinion, yours are expected here.

Well, FFC's purpose of these parties is to introduce characters, plots, and scenarios. Simply put; he wants to set the tone of the relationships between characters. I believe this is BRILLIANTLY done in all of the films. The best... Vito's relationship with Johnny Fontain (sp?) and Vito's relationship/uneasiness of Luca.

It goes a little farther. The parties all take place after a religious ceremony (a wedding, a baptism, and an appointment to a Sacred Order). At the party there are always business meetings going on (Vito doling out favors; Michael and Ola and Geary; Michael Zasa and Vincent) There are also foreshadowings of things to come (Barzini acosting the photographer and Paulie lusting for COnnie's money); Ola handing Michael an orange; Vincent biting Zasa's ear). There is also photography involved where someone gets uncomfortably dragged into the picture (Kay with Michael; Geary with Michael and vice versa; and Vincent with the family).

I agree DonT 100%. Good additions. It's the "set-up"

And might I add that in the begining of all three movies, The Don, be it Vito in GFI or Michael in GFII & III, is always granting an audience to their respective guests, being it the asking of favors or of making business decisions.

EDIT : DonT we must have posted at the same time.

Great minds, Don C......

One other factor:
It's FFC's way of reinforcing that the Trilogy is, first and foremost, a saga about a family. The Mafia is the family's milieu, but it's not a Mafia movie per se. To make an analogy: "Gone With the Wind" is a movie about a family, with the US Civil War as the backdrop. But it's not a Civil War movie.

After the set up there are also elements of the "Godfather movie formula" if I may be so presumptuous as to call it that...

After everyone is introduced the main character always has a brush with death --- Vito being hit --- The attempt on Michael's life --- Michael's diabetic stroke --- followed by a vacuum at the top which gets the family deeper into trouble with their enemies ; Sonny killing Tattaglia Jr, and Michael killing Sollozzo, and the prolonged war; The "assassination" of Pentangeli under Tom's watch; Connie, Neri and Vincent killing Zasa without Michael's permission. This is followed by the main character reasserting himself, but having to take a less aggressive posture --- Vito calling the meeting after Sonny died; Michael pretending to go along with Roth; The pope's death
which temporarily killed the Immobiliare deal, then followed by Corleone style revenge the killings at the end of all three movies. In that respect GFIII differs because it ends with Mary's death and what is perceived to be the end of Michael Corleone as we knew him.

EXCELLENT POINT TB!!! one that I've never thought in terms of. Thank you for that insight.

Yes, indeed. The celebrations serve as a vehicle to make possible what ya'll have stated above. It's an efficient story mechanism - killing several birds with one stone, if you will. But, you might also notice one difference among the films' introduction. GFI and GFIII open with a large degree of solemnity Bonasera in the somewhat shadowed environs of the Don's study and the muted conversations). However, GFII opens with a celebration. Of course, GFI was written and filmed probably without any thought to sequels. So, its introduction is more or less a natural outcome of the authorial process. However, GFIII I see as a harken back to GFI - the solemn, muted, shadowed environemnt of a cathedral. GFII I see as sort of a new beginning, a departure from the almost casualness of Vito's way of dealing with things.