IFrames src changing

hey everyone,
I am developing a website that uses IFRAMEs. I know you can changed the src of an IFRAME by giving it a name and using the usual methods. My question is this:

I have two iframes on one page.
How do I get one iframe to change the src of the other iframe?
I would think this would be difficult.

Thanks,
Brandon

I'm not really sure since I never use Iframes, but try using something like

parent.framename.src = "bla.html"

or parent.document.IfrmName.src="page.html"