In this type of unfortunate scenario, it is best to close the home, then use the re-admit function; it will automatically copy any completed documents. After you have re-admitted the home, remove the parent not longer associated with the home.
To make sure the documents copy over, you'll want to check the Home Report/Activity Type properties of the application for the agency in question.
Make sure the "Copy this report if home is readmitted" checkbox is checked (if it isn't - enable it and choose to update all existing reports).
Close the home. When you readmit the home, it will now copy the documents over.
If there is a current placement in the home, here are the following steps to take:
1. Make sure all of the reports/activities you want copied over once you readmit the home have the setting "Copy this report if home is readmitted" enabled
2. Delete the current placement at the home (delete the placement, not the case)
3. Discharge the home
4. Readmit the home, removing the parent that is longer associated
5. Undo the discharge of the original home
6. Add the placement back to the original home (use the original placement date)
7. Add the placement to the new home
8. Discharge the original home once more