Ideally a case manager will be assigned to your loved one, especially as initial treatment commences. The role of case manager is to ensure that appointments are made, and follow-up occurs. That communication happens across different professionals involved in the treatment. (ie key physical data from GP is passed onto dietitian and therapist). Suitable treatment evolves as time passes and the most appropriate professionals are referred to.
When no case manager is assigned it can fall to the carer/support person to keep the network of professionals afloat and informed. If the professionals your loved is seeing are experienced with eating disorders they may have some informal case management in place. Check and see how your loved and professionals would like your assistance.