ICloud :: Syncing Contacts With Multiple .me Accounts?

My wife and I both have a .mac/.me account. She runs iphone 4s & ipad 2 whilst I run iphone 3gs, macbook and imac. All now run IOS5/Lion and I transferred last week from mobile me to icloud. However, with mobileme we used to share contacts and calendars. I've worked out how we can continue to see a 'joint' calendar' [by adding my account to her iphone for calendar only] but cannot seem to do the same in respect of shared contacts. 

We both have our own contacts which must stay on our own devices but I had assumed that the sharing of mutual data that was submitted by either of us via any our devices would be easier via icloud. Instead it seems harder since icloud has to attach to one or other of our identities, unlike mobile me. Obviously I can go through Clare's contacts in icloud and manually delete each individual of my contacts, but how do I add my contacts that she wants also on an ongoing basis? 

Info:
iMac, Mac OS X (10.6.7)