Optional oneToOne relations and criteria field
I'd put person_id as second field of Report and get rid of notifier_type. Then create a relation persons (persona?) with id field, then make foreign key from Report.person_id to persons.id.

This relation persons (persona?) would have all of fields from both your legal- and naturalPerson relations, plus one additional - person_type. You would have NULLs when a field would be not applicable for given type of person (namely legal_Statut would be NULL for natural person and birthday would be NULL for legal person).

I would then exclude headquarters_address and home_address and make additional relation addresses with person_id field - again, foreign key to persons.id. You would then have a possibility of assigning multiple addresses to persons, mark them as current or previous, whatever you wish. That's what I would do.

EDIT: Visualization