Hello @YanivD,
Since you're in the Custom Design platform, I think the best way to create replicates would be in two steps :
- Create your original design with 12 runs,
- Augment your design (click on DoE, Augment Design, and then specify your factors and response(s)), and then click on "Replicate" for your choice of design augmentation. JMP will then ask you how many times each run should be repeated, so you can specify in your case 4.
Anyway you're right, it's better to directly enter your replicates condition directly in the design generation, to make sure that replicates are well randomized across the design/experiments.
Hope this answer will help you,
Victor GUILLER
"It is not unusual for a well-designed experiment to analyze itself" (Box, Hunter and Hunter)