I think what would work is a Query Backed Relationship (QBR) field.
For example, if each requirement is linked to a document with a particular field (e.g. Requirement For), then you would create a new query that returns requirements. Then create a QBR field that uses this query, and the Field Correlation "ID"="Requirement For" to be visible on the Document.
The field would contain all requirements that are linked to the document via the Requirement For relationship.
QBR fields are not editable by the user; they are updated when the query results change or when the correlation field values change.