Get a couple cat trees.
Get scratching posts.
Two-sided tape for cats - it's 3" wide - to tape on any part of furniture sections to prevent scratching.
Several scratching posts of various materials (my cats don't like sisal rope - they prefer carpet covered posts) or the cardboard scratchers. Cardboard doesn't last as long and needs a bit more frequent replacements.
Put scratching post right up against the place on furniture that they are scratching, that you put two-sided tape on, so they scratch at post instead.
Like relocating a litterbox, you slowly move the scratching post, once they are using it regularly, away from couch spot a few inches a day towards whatever location you want it to be permanently. Or if it works for you, leave it up against the couch spot she's has been scratching.
Train by gentle running front paws down any and all of their new posts, regularly, often, many times a day.
If you catch her scratching something you don't want her to, take her to one of the scratching posts and gently run her paws down it multiple times. Put a scratching post up against anything she's going after.
Don't bring in another cat until you have this girl with better habits - they learn from each other and can pick up unwanted behaviors.
They aren't stupid. They can learn. Just takes consistency, repetition and patience.
Training a dog. Teaching a kid. Studying for a test. Repetition. Over and over and over again, until they learn the habit.
Enjoy your fur ball.