Never do we see an appropriate reaction to Lizzie's confusion and ignorance. When the idea of being flower girl terrifies a shy girl who feels intimidated by the looming presence of strange people, Georgia starts caterwauling about her wedding being ruined, I tell you, RUINED. When Lizzie gets tired and bored of posing for wedding photos and wants cake like the little kid she is, only two people smile ruefully while everyone else is either disgusted (again Georgia), confused (the other Richardses) or terrified out of her tiny mind (Elly.) When Lizzie reveals that she doesn't understand the point of wedding ceremonies by not connecting them to a marriage, Marian goes into safe mode before presumably either telling her grand-daughter the truth or (if Elly is anything like her) screeching about how the child wants his marriage to go zippa-dee-doo-dah so she can stuff her face with cake.
It is powerfully hard to sympathize with ostensible adults who can't be asked to remember how little their children know and assume that their ignorance of a world they just arrived in is inspired by a love of chaos and a need to destroy the mother they hate. It is equally difficult to not point this fact out so that people might know what they're in for.