This is the expected behavior when the option "Propagate tag to each item in a document family” is selected in the settings of the Tag Set (Figure 1):

Figure 1.

This is the expected behavior when the option "Propagate tag to each item in a document family” is selected in the settings of the Tag Set. When this option is selected, all item tags are propagated to each item in the document family. For example, an email and its attachment receive the same tag when either is tagged. When this option is not selected, each item must be tagged separately.

A Tag Set with this option selected is indicated by the following image (Figure 2):

Figure 2.


A Tag Set without this option selected does not display this image.


To prevent this behavior, and therefore enable each item to be tagged individually, de-select the option "Propagate tag to each item in a document family" in the settings of the Tag Set. Note: If the Tag Set has already been used to tag items with option "Propagate tag to each item in a document family" de-selected, selecting the option again will cause the following message to be displayed (Figure 3):

Cannot Change Propagation Setting
The tagset you are attempting to change is in use and would result in inconsistent tag decisions. 
In order to change this setting, first make sure the tagset has not been applied to any items."

Figure 3. 


Further details on Tag Sets  can be found in the Veritas eDiscovery Case Administration Guide.

When the parent, or any other item in a document family is tagged (e.g. attachment or embedding), all the other items in the same document family, including the parent, are also tagged automatically.