Helping nephew's with Duchennes

Hi my name is Kelly shaw I am an Aunty to 2 beautiful boys Kiyan who is 8yrs old and Jaiden who is 7 yrs old both who have been diagnosis of Duchenne muscular dystrophy a degenerative neuromuscular condition this condition affects both of my nephews muscle strength and mobility and gradually over time they will lose the ability to walk and carry out activities of everdaily life independently. They will become fully reliant on wheelchairs in the future. My nephew's are both about to receive new electric wheelchairs which will not fit in my sister's current vehicle (a Toyota Kluger)
So I am asking around charities for some funding assistance to purchase a larger vehicle like a (Toyota commuter) which can be modified to allow for wheelchair access for both my nephews powered wheelchairs so they can safely travel in their wheel chairs in the car.
My sister is a single parent with limited support and is my nephew's primary carer her finances are very tight and she is unable to work due to caring for my nephew's so she is unable to afford a commuter on her own. And in order to receive some funding from the national disability insurance scheme(NDIS) to pay for the wheelchair modifications she needs to purchase a vechile that is no more than 3 yrs old 2015 commuter sells around $45,000 to $50,000 which is way out of her price range even with trading in her kluger. I am looking for some fundraising to help assist with the cost. She lives in Adelaide.