Change fieldB when fieldA is changed

[gimler]

i need to empty a fieldB when fieldA is changed. This works

watch(
    () => values.myForm.fieldA,
    (value) => {
      setValues({
        myForm: {
          fieldB: null,
        }
      }, false)
    }
)

but how can i do this for field inside of array?

Field values.myForm.peoples[].fieldA empty values.myForm.peoples[].fieldB