Interact with Overlapping UI Simultaneously

I'm trying to move the handles of two UI sliders simultaneously.
The horizontal slider is a child of the handle of the vertical slider. I want the handle of the horizontal slider to move the handle of the vertical slider as well. As a default, Unity will only let me select the horizontal one that is on top. How can I ignore the ordering and move both simultaneous?

Also, please don't suggest using a joystick because I already got one from the asset store to work, but it didn't achieve the fluid controls that I was looking for.