How can I insert some view below Y Axis?

My purpose is SCIAxisLabelAnnotation draw above on border line.
like this <– this is just design guide. not a app screenshot.

But SCIAxisLabelAnnotation is can’t overlap renderable series area. So It can’t overlap renderable series area border line.

So I have to customize.
I think that If I add view into render surface, and it’s order make to zero, I can get TOBE result.

My code is below.
Code

But SeparatorView is always on view’s top. So I’m struggling.
You can See result.
It’s covered all surface.

How can I insert some view below Y Axis or SCIAxisLabelAnnotation?

tl;dr I want customize annotation shape and it draw above on 1st top layer.