Building granny flat in bushfire prone area

Hello property experts
Recently I have been asked by a bushfire consultant to get a letter from office of strategic land/DPIE as they own and maintain a land which is adjacent at the back of my property. They basically cut grass every month. My land is in bushfire prone area. Bushfire consultant ask me to get a letter from the department where they need to write that the will do the ground maintenance in perpetuity. I contacted them a few times. They wrote me that they own and manage the land but they cannot write that they will manage in perpetuity which is not acceptable by Rural Fire Service. I have detailed property Survey report and preliminary design. My nextdoor neighbour built granny using the same bushfire consultant. So I thought it would be a easy process. But now he is saying something changed since then. Does anyone have any suggestion for me?

 

Build in Fire Resistant Construction & don't go down the CDC pathway.