Mirror iframe content

I have 2 iFrames in 2 layers on a page one small and one large. there are minimize and maximize buttons - the maximize button shows the large one and hides the small one. the minimize button does the oposite.

i want to be able to make the 2 iFrames display the same content. so if the user navigates around a site loaded in the small iFrame when clicking the maximize button the location of the small iFrame is sent to the large iFrame. catch my drift???