How to change associated iMessage email in conversation?

Hi all,

A friend and I are having issues with iMessage. Basicly her whole family uses the one Apple ID for purchases, so my friend updated to iOS5, and we were messing about with iMessages not realising that it was using their family Apple ID. So we fixed that up by creating her a new iCould ID, setting it all up with that and removing the family ID from the iMessage settings completely, however we are having issues with getting our iMessages working as one unified conversations with our SMSs. It appears that our old SMS conversation has been tagged with her family apple IDs email address on both our iPhones.

To complicate things further we both have iPad's, I've set caller ID on all 4 iDevices to their correct email addresses (completely removing her family ID from iMessage) however now whenever we use our old SMS conversation it's using their family email, as such they're not appearing on our iPad's. When I iMessage her iCould ID, it appears on our phones as a seperate conversation and iPad's. Kind of pointless when its meant to be unified, having SMSs and iMessages in the one conversation trail.

And we're worried that when her parents update to iOS5 that they're going to recieve our iMessage conversation if we use the SMS conversation.

We both don't want to remove our 3+ years of texts just to fix this issue, surely there is a way to fix it so we have one conversation for our SMSs and iMessages in one conversation?

We've rebooting all our iDevices and tripple checked the settings and everything looks right its just that the SMS conversation needs the iMessage email address changing.

After typing this out I just had anothor thought, could it be that the SMS conversations are set to use our phone numbers + family ID, instead of phone number + her iCloud ID?

Anyways, is there anyway to fix this up?