Our back up car seat (its in my moms car) is a GN and DD 5.5yo (37lbs) is still harnessed when she uses it. I am in a jam because my Vivo is not available and DD has a playdate tomorrow and they will take her to school. I was think of using the GN as a booster for the day. What do I have to do to use my GN as a booster? Is it a pain to get the straps out, I am assuming I need to dismantle it? Of course the instruction manual is with the seat in moms car :{