Symptoms may change over time while the underlying disorder remains. The disorder may be periodic, with times of improvement and deterioration, independent of your hopes or actions. You should request the diagnosis and its explanation from professionals. Schizophrenia may be a class of disorders rather than a single disorder. Identical diagnoses does not mean identical causes, courses, or symptoms.
Strange behavior is symptom of the disorder.
Don't take it personally. You have a right to assure your personal safety. Don't shoulder the whole responsibility for your mentally disordered relative. You are not a paid professional case worker. Work with them about your concerns.