She has her own box. Its littler than the others because she is only 4.5lbs and the boys are 10 lbs. They hate her box. She has her favorite blankie, toys and bowl in her crate that she has claimed. I know if I lock Hermes out of that room, even if I move his stuff out, he will sit at the door and scream for her and dig at it. He cant stand for doors to be closed lol. He will make this process hard.I agree completely!
Give her -her own space! Her own food,bowls,water,litter box, blankets and toys.
She may feel threatened to use a litter box that is being used by other cats in the home.
Leave something with her with your scent/odor on it, may it be a piece of clothing (sweater or shirt) or an old towel.
Speak to her softly and re-assure her that everything will be okay.