I do keto diet long term but for other reasons, often the epilepsy version where it's more strict and higher fat.
there are plenty of good reasons we eat carbs (especially complex carbs, plus trying to avoid processed stuff); as a diabetic you just have to prepare ahead of time. it sucks, but honestly, as a 20+ year T1D, not eating cake sucks more than having to plan to eat cake :)
But you have never felt the alternative. It's not just eating cake. You have to see the whole video that I linked to understand the differences (they might not all apply). Think a smoker who've never known what's it like without smoking.
There are many levels to keto diet, and believe me, you can't do the epilepsy version even if you'd wanted, it takes time and hard effort, for children it's done inside a hospital.
So assuming you watch everything they eat, you can keep track of GCM, and try very slowly. Like going from 60-30-10 carb-protein-fat to 50-30-20 ratio, do they have better consistent blood sugar ?
There should be protocols to do this for T1D the safest way.
Watch the video.