[Ifeffit] Help with constrains

Hi all, I am experiencing an issue with CN and sigma2, which are correlated. My CN value is too high, and I would like to reduce it to see if I can improve the fit. I have three questions: 1. Are constraints a viable option? If not, could you clarify the alternatives? 2. The examples I found are in Python, but I am using the GUI. How should I correctly define a constraint? GPT suggested the following: max(4, 12 * exp(-sigma2_O232 / 0.02)), is it correct? 3. I attempted to apply this constraint, but now I cannot delete it. Restarting Larch for each value is not a practical solution. How can I modidy the constraint efficiently? Thank you for your help! Best regards,