Welcome. This is a good place to reach out to.
I'm not T1 or a parent to one, but I can relate being a newbie to this wonderful world that is diabetes.
First thing to know is that T1 and T2 are very different, have different medications and can have different ways of eating (food and diets).
Although Dad and SD are wrapped up in learning, there no reason why you shouldn't learn the theory too, indeed it could be life saving if you do.
Sounds like she will struggle emotionally, have good days and bad days.
It will take you all sometime to come to terms with it all and won't be fixed immediately. It's going to be lifelong for her.
Am sure other T1s and parents thereof will be along shortly.
Meanwhile understand that taking a back seat for a while , and yet learning lots, is a good strategy