Thanks for the advice and reassurance! In the past two nights, we have noticed an improvement in the vocalization - she will still howl but it is not as sustained as it was a few nights ago. We also noticed her being a bit more confident - last night she started using a cat bed to lay in, claiming it as her own. It was one we bought for our girls and they had failed to use it so it is hers. She also jumped on a sofa for the first time so we are taking these together as positive signs - baby steps

She is here to stay and we have grown quite attached to this one who we are calling Nala! Now if we can start to improve the marking we will be good. Thanks again!