But late Friday, Ms. Hayot said that after hearing from numerous schools, the organization would hold a meeting to re-evaluate its position.

WSJ: Admissions Deadline Confusion

The organization declined to make any changes then, saying individual schools could offer extensions to affected families, said Patricia Hayot, a designated spokeswoman for the group and head of school at Chapin, a Manhattan private school.

WSJ: Admissions Deadline Confusion

"By not changing the date we gave our schools the flexibility to deal with all the families on a case by case basis, " said Ms. Hayot, who estimated that 15 to 20% of private-school high-school applicants will be affected.

WSJ: Admissions Deadline Confusion