In order to resolve this issue some unique identification is required for child schema from parent schema under one schema tree.
In the project make any of the below changes :
-keep different number of fields in parent and child schema
-keep different delimiter in parent and child schema
-If there's a requirement to keep the number of fields and delimiter same for both parent and child schema then configure the parent schema with a constant value for one field.
A Document Defect AFIL-2822 ("Unique identification required for child schema from parent schema under one schema tree in File Adapter 7.0.0") is logged to include this in the file adapter document.