Multiple devices getting same text messages
From my understanding, they will probably be getting the same iMessages due to the same iTunes account being used and being the default for iCloud.

What you could do is go to Settings &gt; iCloud and change or create a personal iCloud account for the person.  In Settings &gt; App and iTunes Stores, the original email you used for apps should stay there.

Or just turn off iMessage so the phones default to SMS. This can be done in Settings &gt; Messages.