Maybe I don't understand the question. From this I assume you want a new VI with the same name as an existing one. Just right click the old one and select remove from library. Now create your new vi and save it under the old name and select overwrite. You might want to first move the old one on disk if you think you will need it again. You need to use the library editor window. You cannot just use the OS file manager because that will not make the new VI a member of the class.
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LabVIEW 2012
