How do the rationales of therapeutic approaches for treating somatoform and dissociative disorders compare and contrast?

Somatoform disorders are types of mental health problems in which patients exhibit physical symptoms that cannot fully be explained by medical conditions. Medical test results will be normal or otherwise fail to explain the symptoms. Patients with somatoform disorders will have "higher-than-average levels of anxiety and social dysfunction" (Bauer, M. et al., 2014, "Somatic Symptom Disorder," Consultant). In contrast, dissociative identity disorder (DID), which used to be called multiple personality disorder, is a type of mental health problem in which one person exhibits at least two different personalities. The different personalities will respond with different behaviors, emotions, and reactions. Patients with DID will often have memory lapses, experience losses of time, and be accused of lying. Those with DID often also have post-traumatic stress disorder. Though the two types of disorders are very different in terms of symptoms, one similarity in therapy is that both can be treated, to an extent, with drugs. Studies have shown, especially one conducted by R. Smith et al. (2006), that some drugs can effectively treat patients with somatoform disorders in combination with other therapies. Effective drugs are various types of antidepressants, including serotonin reuptake inhibitors and monoamine oxidase inhibitors ("Somatization Disorder: Top Drugs that Work," Newsmax). Similarly, antidepressants and anti-anxiety drugs can be used to effectively treat DID in combination with other therapies. But, drugs must be used very carefully because drugs can make a person feel controlled, and the feeling of control can lead a patient with DID to feel further traumatized (Dryden-Edwards, R., 2016, "Dissociative Identity Disorder"). In contrast to DID, cognitive-behavioral therapies can be used to treat somatoform disorders, whereas psychotherapy and hypnotherapy can be used to treat DID. One type of cognitive-behavioral therapy that has been used to treat somatoform disorders is mind-body relaxation. To use this method, medical practitioners teach patients relaxation techniques to alleviate symptoms. Techniques include "focused head-to-toe relaxation, abdominal (diaphragmatic) breathing, and mental imagery" (Bauer et al.). Another cognitive-behavior therapy that is effectively used to treat somatoform disorders is cognitive restructuring. Medical practitioners can use cognitive restructuring to "restructure negative thinking patterns" in order to reduce symptoms (Bauer et al.). Methods include asking patients to increase and decrease the severity of their symptoms, teaching patients distraction techniques, and reassuring patients (Bauer et al.). For patients with DID, psychotherapy can be used to help them "improve their relationships with others, preventing crises, and to experience feelings they are not comfortable with having" (Dryden-Edwards). Hypnotherapy can be used to help patients better understand their different personalities, which can in turn help them gain control of their personalities.
https://www.consultant360.com/articles/somatic-symptom-disorder-effective-techniques-diagnosing-and-managing-complex-condition

https://www.medicinenet.com/dissociative_identity_disorder/article.htm