Loading SWFs

I need to load multiple external SWFs. Instead of replacing a targeted movie, how can I load another movie always above the previous?

While the new SWF is loading, I want the SWF below to be visible.

I understand loading higher numbered levels or using layers above. The only problem is what when I return to the lower levels, because they don’t replace eachother, they are hidden by the higher levels or layers.

Is there a general “load in above level” besides having to use numbered levels?

Is there actionscript for this? “when the new swf is loaded, unload the previous swf?”