You can set your GN4 system that, when creating an edition from an existing one, it copies also the specific extra fields of edition, layer and page objects (if defined in a custom schema).

In Editorial Config config object there add one or more optional set of attributes name list, example:

<EditorialConfig ... 

ExtraCopyParamsED="userstr0,userint0" 

ExtraCopyParamsLY="layerextra" 

ExtraCopyParamsPG="pagedata1,pagedata2">

  ...

</EditorialConfig>

Note: the attributes names shown on the previous example are arbitrary: look at your schema to find out the names of your extra fields.

Attributes are copied for any user and when an edition is created from client or from server.