I think I know what the storyline is. When that spaceship crashes all the passengers die except for a baby alien. It crawls away and a little girl finds it and takes care of it. After it grows to adolescence her brother finds out. They both take care of the alien until it reaches adulthood. Eventually their parents find out and the children convince them that it's friendly. The family adopts it into their family. Then the government finds out and tries to destroy it. But the alien instead of running protects it's family from the army and dies to protect it's family.