Project header-DFF issue

Summary: Hi,

As per our business requirement I need to create multiple DFF's(free text) at project header level and when project class code is selected value as 'YES', then the DFF's under additional information should be enabled, if the selected value is 'NO' the DFF's should be disabled/grayed out.

Eg:

Class category: oil and gas

Class codes1: YES

Class Code2: NO

Project header- additional information tab(DFF)

Country name(Free Text);- USA

Percentage%(Free Text)DFF- 20%

Now if, users select Class code as YES, then he/she should be able to enter the values and if Users select the class code as NO, the DFF should be disabled/grayed out