Yesterday I was reading a thread that someone had started, asking if Manchester United had a daughter club in Denmark or something of that nature. It was after 5pm EST, so I could not reply. Nobody had given the answer that I know the guy was searching for and I can't find the thread now because some @ssclown has undoubtedly reported it for no reason.
Anyway, I don't quite have the answer, but to the person who posted that thread, I know what you're talking about and can at least give a vague answer. What you're thinking of is that United has a relationship with some club in South America, that has a relationship with some club in Denmark or something. The South Americans get shipped to the club in Denmark (or wherever it is) so that they can work toward meeting requirements that would allow them to get visas to live/play in the UK down the road. I believe these players are younger teens.
Like I said, it is a vague answer but it gets you on the right track at least. Now that I've got it started others might remember the finer details.....