Three different roles
A case record can involve an author, a subject and an information source. These roles sometimes belong to one person, but not always. A clerk might write about a visitor using information supplied by a colleague. If you attribute the entire entry to the visitor's own knowledge, you silently remove an important step in how the information reached the page. Note each role separately when the distinction affects your theory.
Worked example: the visitor book
A fictional visitor book says Mira arrived after lunch. The handwriting belongs to a receptionist who started work later that afternoon. This does not automatically make the entry false. The receptionist could have copied a note, spoken to another employee or entered an expected appointment. The useful question is how the arrival information was obtained. A shift handover note might answer it; the handwriting alone cannot.
Keep attribution in your notes
Write receptionist records Mira's arrival, source unstated instead of Mira confirms arrival. The first version preserves what you actually read and makes the missing link visible. When another document identifies the source, update that part of the note without discarding the original record. In Somatry, this habit helps you compare messages and interviews without giving a copied account the weight of a direct statement from the person whose actions you are investigating.