You can add new questions to any existing Question Group.
New questions can be added below any question you want by selecting an Existing question  and clicking Add Question 
If you click the Group Name  to add the new question it will be automatically added to the bottom of the questionnaire.
In new Questionnaires click the Group Name  and click Add Question . This will bring up a new window where you can adjust the Question details.
In the Add Question Details, window set the Type  before filling in the details.
If you set the Question Type to Yes/No, the critical status must be set and can not be left blank.