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If the narrator has respect for Maria (and respect for her decision to change her name), they will probably refer to her in the way she wishes to be referred. The readers will be able to keep up as...
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#3: Attribution notice added
Source: https://writers.stackexchange.com/a/28403 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/
#2: Initial revision
If the narrator has respect for Maria (and respect for her decision to change her name), they will probably refer to her in the way she wishes to be referred. The readers will be able to keep up as long as you explain it sufficiently and stay consistent after the reveal. If Maria has strong negative feelings towards her old name, calling her by that name is making the choice to refer to her in a way which makes her uncomfortable. An extreme example would be if your character is transgender. In that case, switching back and forth between names would be not only jarring but insensitive to the character themselves. Even if she simply prefers the new one, you're making the statement that her preference does not matter (to the narrator, at least). This is good though, because it gives you room to say something about each character that refers to her. For example, one character may embrace the new name and make an effort to adhere to it. But another characters might adamantly stick to the old name, or ignorantly fail to remember the new one time and time again (much to Maria's chagrin).