With Release Figures Management, the chapters with the highest returns to their parties (historically) are required to release more women. Grades and recs can be easy cuts to meet those release figures. Some chapters may assume that a legacy will go to that chapter and cut legacies to other chapters also. Some may not. There's no way to know why your daughter was cut from those three. There have been discussions on GC about whether to put legacies on the Panhellenic forms or not at certain schools. Some have felt it was a disadvantage to have that information out there. Others think it doesn't make a difference. Some chapters take great pride in "stealing" a legacy from another chapter too. It can go either way.
Bottom line- She'll end up where she is meant to be
