What the suitable resources in fhir

As a physician, I wants to refer the patient to a specific specialty and specify the number of sessions.
As a specialist, I wanna to open session that doctor specify and add programs and activities.
A physician see that patient need some sessions in conversational then referral patient in encounter to conversational speciality and specify 5 sessions.
A specialist start new session and specify programs and activities in his program in his speciality to patient

@ lloyd

The request from physician to specialist would typically be a ServiceRequest with an intent of ‘order’. If the specialist then wants to create a refined version of the order that specifies more details about what they’re actually going to do, they can do that either using ServiceRequest with an intent of ‘filler-order’ or with a CarePlan. In either case, the resource created by the specialist would have a ‘basedOn’ link that points back to the original order ServiceRequest.