This app lets you load any sms messages into editor and edit the message body, date, sender info, any way you want.
====Note for below the comments
Some users feedback that certain messages can not be edited, I think problem is they do not get loaded, for such case, please load the messages with correct phone number, sometimes it might carry a different phone number even it is in the conversation.
Keyword: sms, edit, editor, tool, alibi
v 1.4 - fix app not working on android 4.4 devices; read more: http://www.cnet.com/how-to/manage-default-sms-app-on-android-4-4-kitkat/