Multiple emails with same Apple ID is causing mixed up with texts and facetime

Hello,

We have set up multiple emails with same Apple ID and it is causing mixed up with texts and FaceTime with my kids. They are getting each others texts etc. I did go under the settings and selected their own emails for each ipod but it is still getting mixed up when its sent.

Do I need to set up multiple Apple IDs or is there a work around this?

Thanks!