I've done a fair amount of reading about the Vatican vis a vis apparitions. I was trying to get to the bottom of the Church's position on Medjugorie. I've never had the least hesitancy about believing in Lourdes, Fatima, and even lesser known ones like Knock. I never believed in Medjugore, and its disciples' main argument was that the Vatican had not yet ruled on it.
I searched and searched. Finally, I found out that the local Bishop makes the proclamation. Then, I read through a big fat book about St. Bernadette, and there it was confirmed for me that the Vatican doesn't make the ruling, the local Bishop does. So, that's the rule of thumb - if the local Bishop says no, then it's no. Yes, then it's yes. The Bishop of Medjugorie, a very holy man, said there was nothing happening there, and the whole Bishops Conference of (what country? Croatia?) even joined him, although it wasn't necessary. The Bishop/s thought that to turn away the crowds would be to spur them on, but they tried to minimize the area as much as possible.
By the way, a friend of mine (since deceased) had been an avid charismatic, and Medjugorie believer. I told her that nothing was happening there. She went on pilgrimage with friends, and came back basically knowing that nothing was happening there.
Well you must be lonely because the Pope and most of the bishops don't believe as evidenced by their refusal to consecrate Russia to the Immaculate Heart of Mary.
Your friend is not like the people I know who went there. They believe in it so much that it becomes their mission in life to spread the word about it.
Several years ago, I wrote to the diocese over there and put a page together on it and have steered some folks to it (not many want to wade through all that but it was important to me at the time because it came up frequently on a catholic newsgroup on the net and people really didn't seem to know that anybody was against the thing). I don't bother with it much any more, but it you want to see, in depth, what the bishop had to say, here is a link if you are interested.
I got very good vibes about that bishop, Bishop Peric. He had a lot to gain by endorsing it, and all he got was grief over it and was under a terrible burden. He even got kidnapped by some fanatics and held hostage for several hours until he was released. It boiled down to a church turf war which is better not to rehash now.
Before I wrote and asked them to send me information about their determination, I had read a booklet by Michael Davies (thanks again, trads) and a couple of things by E. Michael Jones who really opened my eyes about it.