This Wasn’t in My Adoption Plan! - Ch. 1

[MangaDex]

 

[Middleground]

Umm... I'm kind of confused, so i'm gonna type out some key points:

So MC is the glasses girl that worked in the Braunaut duchy as Harvenic's secretary for 10 years pre-incarnation.
At the time she was still the glasses girl, Aerin, the girl she currently reside in, was still alive. But she died due to a [accident] a year after.
Harvenic is still not the heir at the time of her reincarnation.

so, Aerin (glasses girl) can still meet her old self right now, and probably correct her past?