st.lucifer
King
The Slavic population in the region called it Dobrovnik since there were Slavs in the region. It seems from my research that the city was never under Bulgarian rule, however, if it had been conquerer, it would have been renamed. Similar is the case with Thessaloníki, it was never conquered by Bulgaria, however, Bulgarians only call it Solun and had it been conquered, it would have been renamed.
Hadrianopolis, Edirne, Odrin, has held all three names in Greek, Bulgarian and Turkish depending on who had the city at the time.
Was I wrong in my logic?
That's definitely the right way to do it. Thanks for the clarification.