Everyday Use, what theme or central idea is suggested by the conversation about Dee's name?

That would be the theme of heritage. Perhaps the biggest irony in the story is Dee’s rejection of her real heritage for a broader, yet limited, cultural ideal. By juxtaposing Dee with her sister and mother, Walker suggests Dee's new identity is simply a superficial rebranding of herself. She strives to wear her heritage like a unique treasure but ends up shrouded in imitation. Dee reinvents herself using a mixture of academic and romantic ideas of pre-colonial Africa, but her flamboyant clothing combined with her gaudy jewelry make “Wangero” look more like an African caricature rather than an authentic attempt at a cultural shift in attitude. In swapping her name - a familial namesake - for a Ghanaian one, she opts to identify with a less specific aspect of her heritage.