Asking for more $ - HOW do you go about it?

My daughter has narrowed down her picks to three schools, all private. She has a 3.99 GPA and 35 ACT, National Merit commended, plus sports, music volunteering, etc. All three schools came back with about the same financial offer, which is still about 6K higher than our EFC. Since she is theoretically a desirable student, we would like to go back to at least 2 of them and see if we can do better. How does one do this? Do you contact FA, or admissions? Any advice on what we'd say? Thanks in advance.