Modifying F4 help in PA30 Transaction Based on Company Code

Hi Experts,

I have an requirement in PA30 Transaction when infotype 15 is changed / displayed , it takes me to a screen where I need to restrict the F4 HELP for the field Reason for change based on employee company code.

Do I need to modify the standard program or some badi or user exit avaialable.Please advice.

Thanks in Advance.

Regards,

IFF