When you are identifying stakeholders you often receive a lot of sensitive information. "Mr B is drinking a lot, so don't plan any Change Request revision activity on Monday, start from Wednesday or you will not get the correct output ". "Ms A hates Mr C because of their common past incidents. So, she will definitely argue against Mr C's requirements and suggestions, so any meeting with both of them is going to be ridiculous, use only Delphi technique with them". And so on. PMBOK and our wisdom tell us to remove such kind of information from the Stakeholder Register or Stakeholder Management Plan. But you still need it to keep somewhere to keep track your decisions. You write "The Change Control Board meets to review Change Requests every Wensday at 03:00p.m. GMT". But you can not explain why you can't shift it to the Monday morning. And if you, as a PM, will be changed by another PM, how the new PM will manage? He or she was not provided with this important information. And PMBOK doesn't tell us anything about it. )
What do think about it? Is it correct, for example, to make a confidential addendum to the Stakeholder Register? The same thing is about any other documents.