It's hard to introduce a new cat into a household .. espec. depending on personalities … and they've got them just like people do. It would be good to allow her separate space before 'forcing' her to fit in with the group. She's got a whole world of adapting to do … from the home, to the people, to the pets and the furniture, the smells, the sounds, etc.
It's like an orphan coming into a new home with siblings … it's good to give them a space of their own till they adjust. Here's a link to a site that has a great animal behavior specialist. A local contact for me. I hope you find more good tips there. Keep us posted how well it goes. And give that kitty a hug for me.