Parent file - One row per parent couple.  So they can have Mom & Step-Father on one row and Dad & Step-Mother on a second row.

Relationship file - one row per couple with the student(s) they are related to on the same row.  The same student can be in the data file more than once.
  • One row with Mom & Step-Father + Student
  • Another row with Dad & Step-Mother + Student (same student).​