When I was first dxd, I was working in payroll, so reported directly to HR...
That was simple enough.

At my previous job, I told my line manager during a one on one, at my current job, I told my would be line manager as well as the director during my interview...

The one director is a clinical psychologist, she was glad I disclosed upfront, she even drew up a MH annexure into my contract that states I am allowed MH days off.

I work at a small establishment, everyone knows my dx, people knowing has never bothered me, its actually much easier for me to deal with the chance of some asswipe treating me differently, than the pressure of having to hide. The stress would kill me.

Idk if its a coincidence or not, but being so nonchalant about who knows my dx, I've actually encountered zero stigma. I have actually found people to either be willing to be supportive, or curious about what its like to be me...

I would suggest following the correct channels, unless you have solid rapport with your line manager and know they'll go to bat for you, should you need moral support.