Affiliate Marketing Secrets

I’m pretty sure it was elementary school, at least. The book took place in Romania, and I’m pretty sure it was the 80s. The book ends with the spurs of Revolution, I think. The narrator is a girl and she had gotten a red scarf as a present, I think. The scarf was very important in the book, and at the end she gives it away to a boy (or young man, whatever) who has a head injury, to help stop the bleeding. I think her family stood in bread lines, and at one point she is eating M & Ms that she had gotten from a friend, who was a boy, whose father worked for…secret police or something, which is why who could get that. Her mother was concerned when she saw her eating them because she said they could only get chocolate off the Black Market. I believe there was an epilogue talking about how, although improved, Romania was still facing some problems.
Also there’s another book, but I don’t think anyone can find it because I only remember the cover, some characteristics, but not the plot at all. The cover was a girl in a navy uniform sitting down at a chessboard on an island. You could only see her upper torso to her head, and her back was to the cover. The protagonist was a adventurous tomboy I think…? They went to an island…there were rocks…somebody might have gotten murdered…I think someone fell out of a window…I have no idea what happened, but I’m pretty sure it had a word along the lines of “game” or something similar in the title.
If anyone has happened to read these, I’d love to know the titles, thanks!