Sci fi about 2 sisters who develop powers on the run from an organization/group in Australia

[Z3145]

The book is based on two sisters travelling to Australia with their father/unlce ( cant remember which) when an accident happens. I think its a plane crash but not sure. The girls find a briefcase which the father/uncle had with him which has diamonds in it ( they later use it for money whilst on the run). They get hunted down by an organization/group. I think the group captures them and does tests on them. The girls end up developing powers with one of them having telekinesis. They meet other kids. Two of them being brothers with one being able to control air. The other controls fire but Im not entirely sure.

[Kris]

A long shot - Unremembered by Jessica Brody? There are different cover images.

Z3145, around what year did you read this book? A range of years is fine. This will help us narrow down the search.

How old are the main characters?

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