Re: nadia is scared of my parents...
Do your parents smoke? We both noticed a DRAMATIC difference in how the cats related to my husband after he quit smoking. Before, they tended to avoid him and wouldn't like to be held, carried or snuggled by him, always leaving his presence as soon as they could. We just assumed it was because I took care (fed) of them and he didn't spend as much time with them as I did, because he worked. After he quit, they became much more friendly towards him; they would let him pet and carry them and if he sat down, they'd come snuggle on his lap, belly or shoulders.
Are your parents loud voiced at all? Do they move quickly or erratically? It could just be that Nadia needs more time to adjust. Maybe they could try to befriend her with treat-foods?
Sorry, wish I could be more helpful,