So thinking if we could only do private for one maybe we would do dd9 for middle, and then I think there are more options for public high school. But what if dd3 turns out to be EG/HG which would be more complicated? (testing for her scheduled for April after she turns 4).
It is absolutely doable to have one child in public school and one child in private school, and to even have a third child in some other situation. I know I always imagined that all my kids would attend the same schools (and even thought it was crazy when I met a family in which all four kids were at different schools), but we have one in private school and two in public school and it's worked out just fine. We've adjusted things a bit as we've had kids identified as gifted at various levels, from accelerations and skips to changes of entire schools. And, thankfully, the kids are not only no worse for wear, but better off for it. In fact, we're switching things up yet again next year when DD9 starts middle school at a new school. Then we'll have three kids in three different schools.
Anyway, what I'm saying is focus only on your two kids who are in school right now, and find the best schools for each of them -- individually if necessary -- and then figure out a future plan for your younger DD separately when you've gotten a better sense of what she's going to need.
Sorry I'm not any help with Atlanta specifically. It's a great city, though!
