On the student profile's Ancillary Tab you will find a School History section. When a student CTF file is uploaded onto ScholarPack this field is automatically filled with their previous school. For students not coming from another school (or from an overseas school) this will be blank:
In order to report on which students do not have data in this area you can use the History of Schools Report (found at Reporting > Reports > Students (tab) > History of Schools.
There is a Previous School column in this report. If you filter the column by clicking on the header (avoiding the dustbin icon), it will place schools in alphabetical order and any blanks will appear at the top of the column.