guilt f@#$*n guilt!

my parents have travelled to Darwin, they are visiting my oldest brother there. I have never visited Darwin and I haven't planned to in the near future either. I just got a text from the parents telling me to pick up my nieces from Brisbane next school holidays in September and take them to Darwin for the holidays and accompany them on the plane back to Brisbane when the holidays are over. the way it is worded is asking, but I know they telling.
I know my brother would like to see his daughters and Zach does like his cousins and I do have annual leave those school holidays and my brother hasn't seen his daughters since Christmas, Guilt F@#$%*n Guilt!
You see I had plans to go camping across the Nullarbour with Zach, just him and me and maybe a friend from work, on the open road, no constraints, no plans, freedom. Wildflower season, Whale watching, Treetop walk (maybe, heights freak me out!) Wave rock, Open road, No constraints!
But now, I am being guilted into spending my holidays with my brother and my nieces, I can't spend every day with them, they are very high maintenance girls. I want to be a tourist not a babysitter!