I would think a cert.confidential letter from one of the mentioned. I spoke to my bro,he said he didn't have to have anyone with him, but a letter from his pdoc.
If there are certain procedures and rules, they are for reasons I am sure, and if you want this, I'd suggest go along with the rules/requirements/procedures if it's too much and you do not like the procedures, there is the option do not go on disability, or wait.
Please, I do not mean this to offend, maybe more planning may help if you do need a person present, like give whoever you want to come time to put in for some time off to go with you, they can just tell their place of business they have an appt. they do not have to divulge stuff about you, so give it a try.
Lots of luck with this.