here is the setup. i have my imac and aperture 3.2.1 loaded on it. wanted to get it so that both my iphone4S and my GF's iphone4S photostream goes into one photostream on aperture. hope that's not too confusing!
so i have my iphone4S and have my apple id logged in with all the settings i want...no difference here.
i took my GF's iphone4S and went into settings>icloud.
i deleted her icloud info, and put MY apple id in, and just turned 'on' the photostream, and the rest of options to 'off'.
then i went into settings>mail, contacts, calendars.
added an icloud account, with her apple id info this time.
so the icloud photostream option has my info in it...and she still gets her icloud email.
then in aperture, i put my apple id in the imac icloud settings. and aperture pulls from that pref pane.
hope that helps everyone! please ask questions if needed.