Higher tier doesn't mean A*. It refers to the type of GCSE they sit - I was in the bottom division for maths and my division alone sat the 'intermediate tier' maths GCSE whee the highest grade you can get is a B. But you could still get a D or whatever at the higher tier - I probably would have.
At Y9 I would expect them to be assuming your DC will sit the higher tier - plenty of time to enter her for the lower tiers if necessary! But, to be fair, not a lot of people know these tiered papers exist.