You may need to edit an email or SMS to link it to the right user's account to show up in the right Communication Log. You can see more about the default tags here: Which communications show in the different Communication Logs?
Go to the Communication Log and click to open the message. Click Actions on the right then Manage communication tags.
Select the person's name in the Tag Inbound message to drop-down box, and tick the Shared box, then click the green button.