If you have done your clients' measurements as an individual assessments but you need to create a group report afterwards, you can use the Group reporting tool for that. The actual group assessment can't be created from individual assessments because that creates a completely new assessments for all the participants.
Here is how to create the group report using the Group reporting tool:
1. Open Group reporting tool by selecting Tools -> Group reporting tool.
2. Select New Group report from the low right corner of the view.
3. From the opening dialog select the individuals or groups you want to add to the group report (Add individuals/Add groups). You can add both if needed but you need to select them separately. For example, first the individuals and then groups.
4. Select the profiles or groups you would like to add to the group report by clicking the individual name or group from the opening list and then by clicking the Add button. When you've selected all the profiles/groups you want, click Create reports.
5. Next define the report settings and finally click Create reports.
6. Created reports can be found from the list. When you want to open or edit the reports, select Open or Edit button from the same row than the report.
More information about the Group reporting tool can be found from the User guide.