I totally agree with Gail. There is a comfort zone that is very
important here for your cat. But I also think it might be worth it at
least to experiment with the food issue. You MIGHT be able to
encourage her to be just a wee bit more social by trying to feed her
upstairs, even if it happens to be in a spot not too close to the
others. You could try it at least... just move that food dish a little
closer each day... or even on a weekly basis.

All the while, you will want to keep an eye on how the cat responds.

You will have to be very careful with this... you don't want the cat
to go hungry by any means. I am not advocating that at all.

Truthfully, I have always adopted older cats... I have not had very
many kittens in my house. And older cats do take longer to adjust...
but....

Normally they should be eating with everyone else, in the same area,
within a week or two of their introduction to your home.

I have certainly noticed, though, with the adoption of older cats...
there are subtle ways that they adjust differently. Sometimes it takes
them six months to a year to fully adjust to their new surroundings.
Not by way of where they stay in the house mind you... but in more
subtle ways... like where they choose to sleep for the night, or how
they approach the other creatures living in the house... subtle
differences...

That has just been my experience.

Just a thought, nothing more than something to consider :-)

I don't think some experimentation hurts as long as the basic needs
(including that your cat feels SECURE) of the cat are met. You don't
want to FORCE the issue.

But you absolutely want to encourage the cat to integrate in your
household successfully.

With that said, I am sure there are people far more experienced than
I... just thought I would add my own personal experience.

Thanks ;-)

Good luck :-)

However you do it. It is hard for me to tell though because