"I have a problem with W openly disrespecting them."

So, this is a personal boundary issue for you. She is living rent free in your parents home and benefitting from their help and goodwill.

What do you think it would be appropriate to do in these circumstances?

I'm also conscious the disrespect is towards your parents - what do they want to do about it?

T 13 M 7
Me 48 H 46
SS 15
BD 7.14 PA
D final 5.16 (H filed)

We receive & we lose, and must try to achieve gratitude & embrace with whole hearts whatever of life that remains after the losses - Dubus