DLA temporary absence abroad for medical treatment

My disabled daughter receives DLA high rate care and low mobility. She wants to go to Australia to receive medical treatment from a world renowned expert for her conditions. Treatment in the UK has been largely non-existent or unsuccessful. I have done a lot of web research on Gov UK, read the guides here, spoken to DWP officer and all information received conflicts! My key questions are:

What is the current maximum time limit for travelling abroad for treatment without affecting DLA? I understand it to be 26 weeks but the DWP officer said 13 weeks maximum.

DWP officer also said you can only receive treatment abroad if it isn't available in the UK (Disability Rights Handbook says otherwise).

Do you have to get a NHS referral or can it be self referred?

To complicate matters, my father (her grandfather) died unexpectedly in the UK in November 2013 and we all travelled to Australia in December to inter his ashes with my mother's. My daughter had originally planned to go to Australia at the end of January 2014 once she had had time to sort the DLA request and organise treatment, but has ended up having to remain out there with family caring for her as she couldn't afford the flights back to the UK and then out again a month later. My concern is the the DWP will argue that the reason for her trip was to attend a funeral and not primarily for medical treatment.

Any advice would be very much appreciated. Thank you.