I have a Schengen visa issued by the French embassy. My main trip is to France. But I have a sister (sister by heart, not by blood) who is Indonesian and had been living in Sweden for 3 years. I'm planning to visit her for two or three weeks, all cost such as accommodation and food will cover them. What do I need to be able to enter and stay in Sweden?
Do I need my friend to make an invitation or attestation letter for me?