The stallion could be anything. Just because you were told he's a QH, doesn't mean he is. Although, judging by your filly I would bet he's at least half QH. But then again, I'm no expert on breeds.
Your filly is a grade. Regardless of whether or not her sire was QH's, she is not registered as such and therefor no way of REALLY ever knowing. Now, if he gets registered and you register her...then she'll technically be a QH and not a grade. Dumb, I know. But as stated before, unless you want to take her into AQHA shows, who cares! My filly is grade. Although she is 3/4 QH 1/4 arab, she's still a grade. But I could register her in the pali horse registry if I was really concerned. But again, that wouldn't do me much good but to be able to prove what breeds she is.