[Edit: Short version - how do you properly handle namespace collisions in SWC files if one SWC has fewer classes from that namespace than another?]

I have a rather large Flash application which I'm building in Flash Builder (because coding/debugging in the Flash IDE is... not good) and I've got a ton of external SWC files which I'm linking in to my application. This has worked well so far - the file size is on the large side, but it's a lot simpler than loading in SWFs, especially since I am extending most of the classes in each SWC and adding custom code that way (it's a very design-heavy app.) The problem I'm having is when I have Flash Components, like ComboBox or TextInput, in more than one SWC. Whichever SWC was compiled last will work fine, but the others will fail with errors like the following:

TypeError: Error #1034: Type Coercion failed: cannot convert flash.display::MovieClip@1f21adc1 to fl.controls.TextInput.
    at flash.display::Sprite/constructChildren()
    at flash.display::Sprite()
    at flash.display::MovieClip()
    at com.company.design.login::LoginForm()
    at com.company.view::Login()[/Users/ken/Workspace/src/com/company/view/Login.as:22]
    at com.company.view::Main/showLogin()[/Users/ken/Workspace/src/com/company/view/Main.as:209]
    at flash.events::EventDispatcher/dispatchEventFunction()
    at flash.events::EventDispatcher/dispatchEvent()
    at com.company.view::Navigation/handleUIClick()[/Users/ken/Workspace/src/com/company/view/Navigation.as:88]

I've been researching components, ComponentShim, etc. but I'm running up against a brick wall. I thought it might be the fact that some of the components had their skins modified in the source FLA, so I tried replacing them with the default skins, but that didn't seem to help. How can I ensure that I have the components imported and available to all my classes, yet still be able to skin them and include them in my various FLAs? (I am never creating new instances of them, they are all laid out by my designer.)