Cats are territorial animals and your aunt's cats are trying to tell your cat that this is THEIR house and she needs to respect that. Not fair, I know, that it's how cats are.
To try and even things out, why not try locking up the two bad cats and let your cat have full run of the house for a few hours? That way, her scent can get onto things and she'll have a chance to make her presence be acknowledge.
And, your cat needs her own everything (if she doesn't already). Her own bed, her own cat box, her own
food bowl and her own scratcher. These items will be HERS and only hers.
Other than that, I would suggest keeping them separated. If the two cats are having run of the house, keep your cat in the bedroom. And if you're letting your cat have run of the house, keep the others locked in their room (bathroom, second bedroom, etc).
I hope this helps a little.