Hi
@Granny Jill - it's a lot to cope with not just for your granddaughter but for the whole family - it's complicated and confusing to begin with but with experience and practice not just the carb counting but everything else will make sense and become easier, honestly it will.
Carb counting is a pivotal tool in diabetes management and has a direct correlation to insulin requirements. Over time it will get easier and will become second nature. It won't happen overnight, though, so be prepared for - and give yourself permission for - some challenges, some arithmetical hiccups and some unexpected results from time to time. These will all feature and are normal - heck, it's a big thing, after all, and it won't be perfect every time at least to start with. It's so worth it, though, to start right now.
You will get there, though. It's a good idea at this stage to get to know what doesn't need to be counted, as well, so there are treats and staple food items available without the faff of counting. Eggs, cheese, meat, nibbly things like celery, leafy green veg, a few nuts, sugar-free jelly, are all potentially tempting items which don't contain carbs. And there are plenty more than just those I've mentioned.
Hang on in there - you're in it together and the hard work at this stage will definitely pay off not only now but in the long term too. It DOES get easier.
I was 11 when I was diagnosed so I have huge empathy with your granddaughter. Hope she's doing okay.