Or is there need for extending the questionnaire?
Can you help me with putting an sample example of one process in the DPIA register?
The DPIA register is meant to be use as a tool to asses the risks related to a processing activity. Based on EU GDPR art. 35 – “Data protection impact assessment” ( https://advisera.com/eugdpracademy/gdpr/data-protection-impact-assessment/) the need to perform a DPIA is assessed by the controller and this first assessment is done through the first 5 questions in the DPIA register.
The questions within the DPIA register are consistent with the EU GDPR requirements but there is nothing keeping you in adding additional questions and to customize the document for your needs.