Hi LAF,
Why not have your DS9 take the EXPLORE? We found the EXPLORE useful for DD9, a DYS, both for the achievement portion, as well as for a potential tool for academic advocacy. The results were a bit of a wake up call, to say the least. Grade level tests are only going to tell you so much, especially if your DC are not challenged - that is where the EXPLORE comes in. It sounds like this may be the last year it is offered before the switch to Aspire, so I think that would be a good option for your DS9.
The EXPLORE is tightly timed, but is your DS eligible for accommodations (more time)? If you are worried about the time, you could also try the WIAT or WJ.
Since your DD7 needs to wait until 3rd grade for the EXPLORE, perhaps have her take the WIAT or WJ Ach.?
I don't know that I'd get too hung up on what sounds like initial Dreambox levels (I think you can set the start point, BTW). DS6, going into 1st, uses Dreambox and is working right now between 3rd and 4th grade (started at K), but he's worked on it since spring and he really seems to like math (at least right now). Also, he didn't simply "test out" of everything; rather, he's had to work through certain portions of grades to finish them.
I just like test scores for the DYS application - they either qualify this way or they don't (for the most part - their discretion, of course, but often true if you follow others here). We chickened out of trying the portfolio option, because I couldn't figure out what might be "good enough." Others here might be more helpful with portfolio suggestions.
HTH!
