Is there something you could divert her with... For some this is a sign of their own anxiousness/feeling out of place and unsure of what to do to be helpful reaction.

I'm not trying to play devil's advocate in saying that, it's just my kneejerk reaction and I don't intend it when I'm there to 'help'.

Weird as it sounds, does she like anything specific on tv etc.. you could start a habit of when she's going around starting this to distract her and get her to sit down and stop it. A friend of mine who is used to my anxiety uses documentaries to do this, and I didn't realise he was even doing it. Even just shows he knew I liked I'd never watched.

It's now how I get my own friends to fuck off and leave the bloody dishes til after dinner, there an 8yr old and bound to be more when I need help after surgeries etc. Even the ex's mother who I fucking detested would fall for it, and honestly sometimes it was nice to have her speaking to me nicely, excitedly. Sure it was cos the attention was on her and something she liked, but she also ended up shutting up and watching.. leaving me and my home/child in peace haha