I would get the DNA MTHFR mutation test for her. She might not be methylating properly. Another test would be an MMA test. This shows if the B12 is actually working and not just floating around.
A low result in this is desirable, and shows B12 is removing MMA from the body.

Is she taking vitamins? You need to stop vitamins for about a week before testing. Otherwise a false elevation will show up.
If she is taking vitamins on the sly because they are gummies and fun, I'd hide or lock up that bottle.

Peripheral neuropathy may show up in people with Celiac's and/or gluten intolerance. Avoiding all wheat and rye for several months may work.

Vaccine injury is also a possibility. Children are really loaded up on vaccines, and this may be inducing an autoimmune condition.

Also drinking too much juice, or eating sugary foods, can cause blood glucose to swing. When it drops, then the tingles come.

Keeping food intake to whole foods, avoidance of processed and restaurant foods with MSG in them, may help. MSG is very difficult to handle for anyone.

Sometimes a neuropathy culprit is in the home, so becoming a detective, keeping a journal (foods consumed, timing of symptoms, etc) may help discover the trigger.