After the GTRR step, your script can enter find mode, specify the criteria to find records with the specified degree or less and then use Constrain Found Set instead of Perform Find to reduce the found set to only those records meeting your specified criteria.
For some scripted find examples, see: Scripted Find Examples
Most of these example scripts can be modified to use Constrain Found Set instead of Perform Find in order to only apply the script specified criteria to the found set instead of all the records in the table.
I already used Find mode with Constrain Found Set after my GTRR step but the problem is that the field I need (degree) is in the "stud_less" table. The degree field is not part of the results shown on the report. The results are not correct this way because the report is based on the "students" table. What else can I try?
Then your GTRR should be pulling up records on a Stud_Less layout, instead of Lessons. A layout based on Stud_Less can include any fields that you need from both Students and Lessons in order to produce the needed report.
OK, it worked! Many thanks!