You can create a Dynamic Group for your 'looked after' students by going to Reporting > Data Digger.
Enter "In Care" in the top dropdown menu:
Please refer to:
A number will appear in the blue circle, indicating how many students currently fulfil that criteria: as a Dynamic Group more will automatically add to the group, or others leave, as students marked In Care enter or leave the school.
Click on the figure in the middle of the circle, you will be given the name of the student(s) who fulfil "In Care" status, as well as the percentage of the students in the school falling into that category.
Enter a name for the Dynamic Group, then click Create Dynamic Group to save this group.
Then, go to Reporting > Reports > Attendance (tab) > Percentage Attendance Between report
and from the Group drop-down select the Dynamic Group you just created under the Dynamic Groups area.
Run this report by this group and you will obtain the attendance data for individual students who are In Care.