Hi there
As a intro, My friend (whose name is parvati), along with 300 other people (including me) are on a festival tour in Poland.
Parvati lost the envelope which had her RUSSIAN passport, a valid Scengen visa, and other documents. She is here with no legal guardian, and her parents are in Russia.
Recently the Polish police came here, and checked all of our passports.... When they came to know about her, they took her away (not handcuffed- just normally) to the local polish station
The latest news is that they put her in a juvenile prison. (AFAIK she has committed no crime). She is a vegetarian, so someone from our group has to bring her veg food.
The police said: Parvatis mother will have to send her a copy of all documents possible --> these will be sent to the Russianconsulate to confirm they are real --> after this she will be deported.

Questions.
Is this legal?
What to do?