I have experienced and read numerous frustrations regarding converting assignments of HE Marshall's Our Island Story and This Country of Ours published by Yesterdays Classics to other publishers such as Wilder. I have developed a spreadsheet which has a workbook for converting those two publishers chapters and pages. I am happy to send it to you if you email me at
bill.hevener@gmail.com (please keep email address confidential)
Using the worksheet plus inserting chapter numbers on each chapter heading of the Wilder edition will make life easier for you and your student. I hope this helps you as much as it did us.