Currently Being ModeratedFeb 14, 2013 3:11 AM (in response to AmyJudd)
That's because everyone is using the same Apple ID for iCloud, iMessage, FaceTime, etc. For that stuff, each of you needs their own Apple ID. You can create an Apple ID here:
Must be a verified email address. If you don't use separate Apple ID's for iCloud, etc., you'll have stuff like this happen.
You can share the same Apple ID for iTunes content...no issues, but for everything else, everyone should have separate Apple ID's.
Right now, on the other devices & yours: Settings>Messages>Send/Receive...edit here, or, ideally everyone needs to get their own Apple ID for iMessage, etc.