Looking for help on car seats! My 3.5yr old daughter is just about to grow out of the impact shield on her Recaro Monza booster seat and I'm feeling very uncomfortable about her using the adult seatbelt in its place. Think I may have made a mistake buying this car seat and have considered buying another car seat with a 5 point harness up to 25kg and then switching back to the Recaro Monza after that. But that's a big expense I wasn't expecting, and wondered if anyone can advise on the Belt Upp safety belt attachment as an option? Does it offer the same (or close to the same) protection as a 5 point harness? I can't find any real info on it other than what the company produces and I'm afraid it might actually be less safe because of the way it only harnesses the upper torso. Any help gratefully received! Thanks!