I'm currently doing a pre-doctoral internship in Europe. I currently own a citizenship that allows me to stay in the Schengen area only for 90 days. However, I'm expecting to get Hungarian citizenship quite soon. In fact, the lawyer I hired said that my citizenship is confirmed and only needs to pass registration so I can get a birth certificate, with which I can get a Hungarian passport.
Can I extend my stay under these special circumstances in the Schengen area? If not, do I need to exit the country and apply for a student visa? Will a letter from my professor help?