Andrea Gross has amended his $20 million lawsuit against the plane manufacturer, the pilots' estates and others by adding a wrongful death claim, Los Angeles court papers show.
"The crash ultimately caused Adam Goldstein's death at a later date," the papers state.
Friends and associates of the musician have widely blamed his trauma from the September 2008 plane crash as leading to his fatal relapse in August.
A trial is set for March 2. A number of opposing lawsuits have been filed in the case.
Learjet has previously denied all responsibility for the crash.