ASD 8 year old makes a raspberry/spitting noise when she's tense/stressed/Angry. I need to stop this, but how?

[Wills]

When dd1 is angry (which feels like most of the time at the moment) she makes a raspberry/spitting noise/action. The problem is that my younger two children are picking up on this and copying her. Whilst I can explain to the 5 year old that she doesn't do it (with lots of reminders ) its impossible to explain this to the 2 year old who is now going around spitting into everyone's face! Admittedly its better that she makes this noise than hit her siblings (which she also does an awful lot) BUT nevertheless I do need to persaude her to do something else to let the stress out that is less socially unacceptable. Any suggestions please.

hi i have a five year old with asd they tend to always have what i call a thing raspberrys is hers when she stops doing that she will replace it with something else my boy was blinking then changed to a cough as if he was clearing his throat now he sucks his top the more you coment about it to her the more they do it hope this helps