Help please

There was a film on Horror Channel in the uk a few years ago, it wasn’t a big film probably something shown at Fright Fest.

Anyway there was a girl who is possessed (not the Exorcist) 2 sisters, one is a teenager and the other one is very young.

It was thought that the little sister was possessed but in the end it was the teen, she was walking down the street at one point and there was a swirling grey mist or cloud around her. When people came out on there doorsteps to see what was going on, she directed tendrils of the grey mist to them and they turned to dust or ash.

The teen, I’m quite sure is an Australian or New Zealand actress from Neighbour’s or Home and Away.

Right at the very end she was waiting for a bus or something on a country road, after we thought she had died.

That’s all I can remember, as it was on quite late.