I had kittens a year ago. I have now been spayed but having kittens was a mistake for me. It all went well. There were six of them and five of them went off to new homes. But, alas, my human kept one of the females back. There are now to of us in the house and we don't get on. I spend most of my time outside, even in the cold weather, because my adolescent daughter is larger than me and a bit of a bully. What can I do?
This is the result of humans thinking we cats are like them. (Luckily for our pride and dignity we are not!). Or worse still they think we are like dogs, always looking for other dogs to play with and desperately in need of doggy pals.
Fundamentally at the heart of most of us cats is a solitary hunter. We don't share. We don't pack. Some cats can live with their relatives but many can't. Actually humans often find out that living with a teenager is hard work, so it is ridiculous for them to assume we are so family minded that they can just assume we want to live with our relatives without asking us. Would your human like to live with her grown up daughter? Or her mother?
If you were living in the wild, you (or your daughter) would just move on and live in seperate territories unless there was only one place of shelter. That would be the natural way of life but humans have never grasped that they are asking us to live in very artificial surroundings. As it is, you are stuck with her. Have a careful think about the house facilities. If she is sleeping on the bed, could you find room in the spare bedroom, for instance?
Could you persuade your human to put down two feeding locations so that you can eat in peace without having to be near each other. Probably not. Humans get stuck in behaviour patterns and are not willing to change. They imagine we like eating side by side. We don't. We wouldn't be eating our mice side by side. We cats eat privately if we live wild. Luckily you obviously have a cat flap so you needn't share the litter tray with her.
The other obvious way out of this problem is to start visiting the neighbours. This is particularly important in winter. If you can find a suitable human, who will provide good food and has enough heating in the house, this may be the moment to re-home yourself. Plenty of cats do this. Or you can compromise and simply spend most of the day with the neighbour just coming home at night. Timesharing your company with another human might work out well.
PS No advice for a bit. My secretary is going away for two weeks to visit her brother. She certainly couldn't live with him for longer than a week or two without quarrelling.