2.6.2. SDC File Precedence
Click Settings > Timing Analyzer to add, remove, or change the processing order of .sdc files in the project, as Step 1: Specify Timing Analyzer Settings describes.
If you use the Intel® Quartus® Prime Text Editor to create an .sdc file, the option to Add file to the project enables by default when you save the file. If you use any other editor to create an .sdc file, you must add the file to the project.
The .sdc file must contain only timing constraint commands. Tcl commands to manipulate the timing netlist or control the compilation must be in a separate Tcl script.