In our opinion, Uda doesn't get nearly enough respect in this novel.
First of all, she basically raised Codi and Hallie, taking care of them for ten years after their mother's death. Now that the girls are gone, she takes care of Doc, too. Yet in spite of everything she's done for the girls and for Doc, Codi doesn't so much as remember Uda's face when she runs into her again back in Grace. Burn.
Forgetting who Uda is entirely is probably the most intense manifestation of Codi's lost memory. It's not just a single event—it's a whole relationship with the only adult who seems ever to have hugged her as a child that's dropped out of Codi's mind.
Uda keeps on supporting Codi once she's back in Grace. She bakes for Doc, she helps Codi clean out the attic of the house in a pivotal scene, and she reminds Codi of several important memories. She even knit the afghan that is basically still Codi's blankey up until she buries it in the novel's next-to-last chapter, and it's Uda who puts the final offering, a bouquet of zinnias, in Hallie's memorial.
In spite of her centrality to Doc's, Codi's, and Hallie's lives, descriptions of Uda throughout the novel retain an oddly dismissive tone. She's not that bright—she basically thinks that Codi's been off cavorting in France—and she often conjugates her verbs incorrectly when she talks (8.5-11). Also, Codi literally calls the zinnias Uda brings for Hallie "homely" (27.25). Uda is described as "a heavy set woman" (8.5), as having small feet and a shiny face, and when Codi finally remembers her, it's her arms "when they were thinner" (23.75) that come to mind.
Basically, Codi's kind of down on Uda. What's up with that? Is Codi just a fat-shaming jerk? Well, maybe, but we think there's more to it. Remember, Codi has always felt like an orphan on the one hand, while on the other, Doc has raised both girls to think they are above everybody in Grace. Uda kind of gets the worst of that. She watched the girls at night when they slept, she baked pies with them...but she's not their mom.
Codi's relationship to Uda offers a window into her mixed-up brain. She thinks of herself as an orphan, even though she's always had a family in Grace, which is full of people like Uda. And the way that she reacts to Uda's language and her body might reflect on the fact that despite herself, some of Doc's arrogance has crept in to Codi's relationships.
That's why it's no coincidence that it's Uda lays the final objects down in Hallie's memorial. Even if Uda never gets acknowledgement from Codi as the family she is, the narrative still emphasizes her importance. She's been there taking care of the Noline girls all along.