I think if you got 99.85 then you would be absolutely certain to get in. The merit one is the $6500 one for people who got between 99-50-99.89, right? (They only changed it this year, it used to be different).
If you've gotten an email offering you a merit scholarship then you should be fine. You do realise you can't hold a national merit or national undergraduate scholarship as well as a PhB scholarship, right? You only get the PhB one if you didn't get offered a merit or national undergraduate one in the first place.
In short, you're pretty much certain to get in. Stop worrying
You only find out if you got into PhB ahead of the main offers if they offer you a PhB scholarship... which you were too good to get anyway.