You can edit a fragment by selecting the fragment reference in any form. When you select the edit option, the fragment source file opens in LiveCycle Designer ES and the fragment is selected.
You can rename the fragment or modify the form objects in the fragment. When you save the fragment source file, your changes are immediately reflected in all open forms that reference the fragment. You do not need to reload the forms to see the changes.
Note:
Renaming the fragment subform in the Hierarchy palette in the referenced XDP file breaks all references to that fragment. You can change the fragment metadata name in the Fragment Information dialog box or in the Object palette.
When you edit a fragment, all forms that reference the fragment reflect the changes when you save the form in LiveCycle Designer ES. If you update a referenced fragment after you save a PDF form, the old fragment is still visible when you view the PDF form in Acrobat. To update the fragment that is visible in the PDF form, you must resave the PDF form in LiveCycle Designer ES
See also 

To edit a fragment