Question about crash responsibility at intersection.

My father was involved in a car crash some time ago as an uninsured driver (yes i know he should have been insured i have told him this), and the insurance company of the other driver is claiming he is at fault and requesting payment for the damage, my father believes he is not at fault and we have video footage of the accident from a third party.

I do not drive and don't know enough about road rules to make a judgement on the situation so i would appreciate anyone with more knowledge about this chiming in, as i can not post a picture or diagram i will do my best to describe the incident, which happened traveling north-east on Lorne street at its intersection with Queens lane in Melbourne.

At this intersection the road widens into two lanes, the other driver was remaining in the left lane preparing to make a right turn and my father changed into the right lane to attempt to overtake and keep going straight, they collision occurred when the other vehicle turned right in the middle of the intersection.

While normally i would be more confident that the other vehicle was at fault for making a right turn without checking that the lane to its right was clear and not giving way, I'm less sure in this situation as the road only widens out into two lanes in the 20 meters leading up to the intersection.

I would appreciate anyone's understanding or opinion on who is at fault here and if we should be expected to pay for the damage caused, and am happy to provide any details that might be relevant in the comments.