Illigitime

That’s like the original time line. Now MC is back in her original world having left Korea.
She is only perceived as the illegitimate child of Perdia. MC’s actual father is that guy in the glass coffin in a comma. How her mother got her to Perdia and made them believe she was his child is still a bit of a mystery though.

Spoiler
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The duje and duchess of Perdia knows her real identity. Her mother and She used to live in the annex together. Then oneday she told the duke and duchess to take care of her daughter and left.