The Amityville Curse (1990) has very little to do with the series. Why did they call it this then. I guess nobody would want to rent a movie called "The Spooky House" or the "The Curse of an Evil House". In their infinite wisdom, the producers probably sat around in a smoky room thinking up of ways they could market this film. "Hey, how's about we make another Amityville Horror movie?" "Why" asked the second Producer. "They just made another one for T.V. So hears what we do, we finish the film and just loop in a mention of Amityville House. If we's have to," explained the Executive Producer. "If that's too expensive we'll just make up a scary poster and video art and leave it at that."
You know what? That's probably what happened. Bad movie that's nearly unwatchable. But it's fun to make fun of if you're in the right mood or if you're hanging with some friends. Other wise avoid it like the plague!