We adopted a 1 year old female fixed cat from the humane…

Your cat has defined her territory and has and is quite comfortable in it.

The new cat now has to define her's in order to feel safe and secure. With cats it's all about safe and secure. Instinctively the are solitary animals. No pack or herd for protection.

If you could please describe for me how their interactions go, and what steps you have already taken other than Feliway.

Is outside the whole outdoors or to an enclosed area?

That is not meant to be judgmental either

That is great and may make this much easier. Does Carly have access to the outdoors and knows how to use the door?

Here's my suggestion. Provide a separate small inside space for Carly with food, water, and litter box. It can be a room, a crate, or even a corner where she now spends most of her time when you are not there. Have Lacey keep her regular food/water/box location. Try to keep Carly in that area without intrusion from Lacey. Once Carly knows she has her own secure space, she will be less likely to confront Lacey over the whole house. Outdoors and the whole house will seem neutral to her. She will, however, probably always challenge Lacey if she comes to her space. Or maybe not, especially once she has outdoor access.

With cats it's all about secure territory, however they define it, and whoever they decide to allow in it. That is normal cat behavior that has allowed them to survive for thousands of years.

Perfect. If that's where she is comfortable, make that hers.

And thank you for providing a home for a shelter cat. I'm sorry it has been disruptive.

If she scratches and meows that is not where she wants to be. Put her things in the area she spends most of her time when free. That is the spot she has chosen.

Hope this helps. If so please click<accept> so that we will be here to answer other questions like yours. Thank you and kind regards!