I would consider talking to your pro shop technician, first of all. Nobody here has ever seen your daughter throw a ball, so we are all making educated guesses.
If your daughter is beginning competition on challenging oil patterns it is vitally important to start looking at patterns from front to back as well as left to right. The left to right reading of a lane is all that most league bowlers do and that is not nearly enough for attacking sport conditions.
That said, I have no clue how many balls you have in mind, but the best thing you can do for assembling an arsenal is to have balls that range in the amount of friction they create on the lane (left to right hook) and vary in their speed of response (smooth to angular).
In a perfect world, a bowler's arsenal would be at least 5 balls (6 if you use a polyester spare ball).
1 for general heavy oil use (moderate speed of response)
1 for general light oil use (moderate to fast response)
3 for medium oil use (slow, moderate, and fast response)
As the product line stands, I would likely end up with:
Raptor P7 or 2 Cruel (Heavy oil, general use)
Venom Strike (medium oil, slow response)
Sigma Tour (medium oil, moderate response)
Primal Scream (medium oil, fast response)
Ascent Pearl (light oil)
I tend to post on here a couple of times a year and when I do it's too long. Sorry about that.