Share Photo Stream and Contacts but backup to different iCloud accounts

Question

I have researched this question a bit and found remotely similar questions but none exactly the same (feel free to point out an answer that answers this already).
Is there a way to use a joint iCloud account between my wife and I (so Photostream and contacts are synced), but have the phones backup (to iCloud) to two different accounts?
At the moment, the "main" iCloud account on both iPhones shares the photostream and contacts - which is great. I've also installed another iCloud account (on each phone, i.e. three iCloud accounts in total) with the calendars shared between each new account and to solve the problem with Siri automatically switching who we are (see https://discussions.apple.com/thread/3411497?start=0&tstart=0 for this problem, which I have fixed). Ideally, I would like each phone to backup to these (new) accounts due to space restrictions, not the shared iCloud account.
Currently, it seems, I can only backup to whichever account the Photostream comes from - is this correct? If not, how do I get around this?
(I consider iTunes as a completely separate entity but FYI, iTunes on both iPhones uses a shared account - one that is completely separate from all the iCloud accounts mentioned above).

Answer 1

To migrate to a new account and keep your data and photos, start by saving any photo stream photos that you want to keep to your camera roll (unless already there) by opening your my photo stream album, tapping Select, tapping the photos, tap the share icon (box with upward facing arrow), then tapping Save to Camera Roll.  If you are syncing notes with iCloud that you want to keep, you'll need to open each of your notes and email them to yourself so you can later copy and paste the text into new notes created in your new account.  Then go to Settings>iCloud, tap Delete Account (which only deletes it from this device, not from iCloud), provide the password to turn off Find My iDevice and choose Keep on My iDevice when prompted.  Then sign back in with a different Apple ID to create your new account and choose Merge to upload your data.
if you are signing back into the same account, just with a revised ID you should choose Delete from My iDevice when prompted as your data will still be in your account and will download back to your device when you sign back in with the revised ID.  You do still need to save your photo stream photos to your camera roll before deleting the existing account.