Hello again, I just added source of type "Test01", using "TestSourceId" as the alias/import column name as you directed; however, not every Sample of this Type (in this case PBMC) will share the same source of type "Test01", because there will be other projects, i.e., "Test02", "Test03", etc., with different Patient Visit schedules collecting the same Sample Type (PBMC), so if I add the source of type "Test01" to the PBMC Sample Type, then the "Test01" reference will show up even for PBMC collections that aren't part of the "Test01" project.