>I have a couple of comboboxes, and then below them I have 2 containers (invisible) that contain other objects. The containers will only be visible when they are required, so they will be made visible dynamically.

I would make this into a pageframe. Put each of the containers onto its own page, turn tabs off and get rid of the border. Then just flip the active page property when you want the other container to be shown.

>Should each object have it's own code in the refresh? Should the controls be manipulated from just 1 program?

It depends on where you want to maintain it. Personally, I'd add code to both controls so they can handle them selves. But that does mean I have more code spread out. But it also means, if I want to find the code that hides a control, I know to look right at the control.