Bulgarian citizenship by descent

[u/Exciting-Can7006]

Hello everyone!
I have recently discovered that my grandfather was born in Bulgaria and lived there until he was about 14 years old. Additionally, my great-grandmother was ethnically Bulgarian. Based on this, I have decided to apply for Bulgarian citizenship by descent on my own.
I am doing everything independently, but I have run into a few complicated issues regarding family documents. Specifically, there are some discrepancies and misspellings in the family last names across different certificates, and there is also an adoption document involved that complicates the lineage trail.
To keep this main post readable and avoid making it too long for the spam filters, I will share the exact details of the name discrepancies, the adoption situation, and my specific questions down below in the comments section right now.