There's a carby breakfast, and there's a carby breakfast. Anything that's relatively quick acting is really hard to balance timing with. Let's also bear in mind that the other piece of T1D is that in the early stages, you tend to have faster gastric transit than a T0. You will find that if you continue with her current breakfast, you may need to bolus even earlier in advance.
Secondly, your team won't be up with the idea of not eating huge amounts of carbs making avoiding spikes much easier to live with, but then, they aren't T1D so don't really know what it's like to be T1D or a T1D child. The only people at my clinic who accept that is okay are the two consultants and oddly, the dietitian. And one of them is still a little reticent about it.
The alternative is to modify the breakfast to maintain the number of carbs but make it slower absorbing, so fruit and cream, or yoghurt, etc. If you are feeding breakfast cereal and toast as the main food stuffs, they are two of the fastest acting food types outside of pure sugar. Sadly.
So the spike is going to be difficult to manage, and you definitely don't need to try and surf it down if you are already returning to a low level. That's a sign that too much insulin was given not too little, & that the timing wasn't right.