well, an opening scene with Mary's funeral will be great and not really a change as you may believe. I mean, weddings, funerals and other religious events are nothing
but different faces of the same medal. The occasion may be different, but the reason why people gather is all the same: to be there, to take part in some important event in someone's life. The "party" is the, so to say, mundane facet of these celebrations, the deeper spiritual meaning of these rituals being the role of the community, the people of God attending and accompanying a fellow member of the comunity itself in a crucial moment of his/her life.

Conclusion, I'd definitely vote for Mary's funeral as the opening scene of this - God forbid! - GF4!