1.  In Administration, select Globally Change Records
2.  Start a new Applicant or Student Change
3.  Scroll down on the Available Fields and expand Education
4.  Select Feeder School
5.  Select <All> to change any/all Organization Types listed (if they are listed on the records), or Selected Organization Types and select OK
6.  Operation: Add 
     Add: Checked
     Select OK
7.  Filter on any desired Applicants, Students, statuses, years apply, grades apply, etc
8.  Preview Changes
9. Select Change now if the preview looks correct

NOTE: This will check all Applicants or Students that meet the Filter criteria.  If they have any of the Schools listed from step 5, it will mark them as Feeder Schools