Everyone is correct, you need to get this cat eating again. If need be the vet and/or uncle needs to force feed... Not eating does cause fatty liver disease - cats, unlike people, can't convert their "fat" effectively into energy to live off - and when they start to convert fat to food for longer than a few days, develop toxins... that can lead to death.
If it were me, I'd get a nice sweaty piece of my clothing - and put it with her, near her bowl.. so she has my scent to "comfort" her. I'd put another piece of clothing (say an undershirt I've worn to bed or worked out in)
by her sleeping spot, no matter where that is (under the bed, whereever).
I'd also make a tape of my voice - and play it for her in "her" room - keep her in one room and gradually let her out to explore uncle's house.
Maybe go visit a day / night and sleep in the room with her? If its possible -
I don't know the situation.
If at all possible I'd opt for me visiting her, rather than taking to vet - vet
is so stressful and that's the last thing this kitty needs. She's obviously bonded closely to your family, and is confused and upset by the change.
To tempt her to eat : smelly foods - sardines, tuna, canned chicken w/
broth...or her favorite "treat" food. Baby food can be used in a pinch, just as long as it has NO onion or garlic powder in it...Shebs loved chicken and turkey organic babyfood when she was getting over her tummy upset.
Diablo insisted on having cooked chicken or canned chicken w/ broth. (Which I happily roasted and cooked for him, I was that glad to have him
eating and pooping again!!)