Please add to the relationship "composer" an attribute "dubious". The attribute is required to describe a case when a work is usually attributed to a particular composer, but there are significant doubts. A typical case is when a catalogue of composer's works contains such remark.

Example: Luigi Boccherini, Trio Sonatas G. 143 - 148. These works are listed in Gérard catalogue as "dubious", although no better candidate is suggested.