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1. Validate preperson_id UUID

   1. In case of error - return 422

2. Check preperson_id doesn't exist in mpi.persons, but exists in medical_data.patients as patient_id. It means that preperson_id relates to preperson, but not to person.

   1. In case of error - return 422 (Such preperson doesn't exist)

3. Check preperson status is active in medical_data.patients

   1. In case of error - return 409 (Preperson is not active)

4. Check if exists another preperson merge requests with status NEW or APPROVED for this preperson

   1. if exists - update status to REJECTED

5. Check if preperson has at least one episode

   1. if no episodes - return 422 (Preperson has no episodes)

Validate employee

1. Extract user_id and legal_entity_id from token and find corresponding employee_id

2. Check employee status is APPROVED

   1. In case of error - return 422 error (Only active employee can create preperson merge request)

3. If employee has division - validate it has status ACTIVE

   1. In case of error - return 422 error (Only employee of active divisions can create preperson merge request)

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