Thank you both for the advice
Rosie is mainly in our room, so Sadie has full use of the house, it's only when Rosie goes near her to play , that she hisses and growls.
Rosie isn't phased by any of this and tries to get as close to Sadie as she can
I have been giving a lot more attention to Sadie when they are in the same room too.
I think I will have to be more patient.
I've never heard of the feli-way plug-in before, I'll look it up
Thanks again