How to grey out a particular field while creating PIP document

Hi ,

In PIP document creation , is there any way to grey out the a particular follow up. For example, While creating PIP document there will be three follow up's ( First Follow up, Second follow up and Final Follow up). As per the requirement i need to grey out second and final follow up when the user is going to create First follow up.

Thanks & Regards,

Ganesh R K.