How to save text messages from iphone 4?

I recently upgraded my iPhone 4 to an iPhone 5s.

I had previously promised my daughter that she could have my iPhone 4. However, there are messages (that happen to be a disagreement between me and her father/my ex-husband) that I need to save, but don't want her to see!

How can I save these messages or send them to my new phone?

Just forward them to your new phone then delete off the iphone 4