Alana has developed a seemingly incurable condition: I-don't-want-to-share-cause-I-was-an-only-child-for-almost-three-years-and-you-can't-make-me-share-or-I'll-scream-really-loud-itis. The symptoms include: screaming at your cousin for attempting to play with a toy that you weren't even looking at until he picked it up and now you really want to play with it all of a sudden; being a poophead; throwing a toy at your cousin for refusing to give you his stuff (even if its the pants that he's wearing); crying; being as stubborn as humanly possible; being cute right after being bratty so that no one will hold a grudge.
There is no known cure for this condition. If your child develops it I wish you the best of luck because you will want to immediately list this child on craigslist to whoever calls you first. Why craigslist and not Ebay? Ebay charges fees and shipping, plus you have to wait for payment. Craigslist is free.
Trying to make the stubborn child share is pointless, she will not. You will end up with a pile of "unshareable" toys on top of the entertainment center at the end of the day.