The ivy league schools market themselves as need blind. I’ve always been skeptical of this fact. Mysteriously every year they have roughly the same percentage of students who need aid. And the bulk of internationals are all full pay. I’ve always found it strange that most of the admissions directors are also head of the financial aid departments. While they say that the decisions are independent of each other, I’m not so sure.
What I think happens is that after a first pass, students are divided into three piles: accept, maybe, deny. They then go through the accept pile to make sure the institutional needs are met: males vs females, majors, geography, race, etc. At Duke, they call this “sculpting” the class. At every step along the way, I’m sure they are running the total FA numbers. The wealthier schools like Harvard don’t rely on tuition revenues as much as smaller colleges. So the weight that each college places on FA during the sculpting rounds may vary. They use sophisticated multivariate modeling to predict the incoming class composition.
But for Ivies, I’m not sure applying for FA for your current child will have any impact on the decision for child #2. If you need the aid, just apply for it. Ivies are generous with aid, so take it.