After marriage

[horsedaughter]

Hello, everyone,
I am wondering about Spanish naming custom. From what I understand, a woman does not legally change her name upon marriage. She will keep her given name + paternal surname + maternal surname. However, this married woman may informally choose to drop her mother's surname and append her husband's own, or she may add his surname following "de".

My question is, since this is not a legal name change, in which social situations would she go by "Señora de husband's-surname" or "Given-name Paternal-surname de Husband's surname" or "Given-name Paternal-surname Maternal-surname de Husband's surname", etc?

Or would it be more appropriate/common to use only her legal name? For example, how would she introduce herself to people at a new church after getting married?

I apologize if the question is not clear; English is my second language and Spanish soon my third. I thank you for your help.