Hi Val,
I think the need/decision to take/skip Pre-Algebra is really curriculum/school district dependent. So much of elementary school math circles around and repeats itself these days that it drives me nuts
And my kids nuts too
But after having looked at how to subject-accelerate two of my kids now in math, I've found that you really just have to look at what is offered/taught on a case-by-case basis. My ds, for instance, jumped into and had to take Pre-Algebra, and that was ok - he didn't repeat anything substantial at all the in his Algebra course. Now that I'm looking at my dd's situation, every single darned piece of course curricula I've looked at from 5th grade "normal" level through Algebra looks almost the same - it's nuts!
Soooo.. I'm no help at all re whether or not to skip Pre-Algebra. In your case, if I were you, I'd trust my gut feeling because you've worked closely with your dd and you're familiar with the curriculum at the school she's going into (I think - don't you have an older child that went there?)
How would you advocate for it? Use anything and everything you have that shows what she's already mastered in math. There is also an "Algebra Readiness" test that I think is widely available in most school districts, so you could request she take that - or you could request that the school pre-test her on the Pre-Algebra topics. If you've looked over the curriculum and the topics really do look similar between each course, I think she'll be a-ok with skipping. You can always provide support at home when she hits something she missed by not taking Pre-Algebra.
Best wishes,
polarbear
