Are headers and numbers added in each subdocument or can they be added into the master document later?
The master document rules the formatting. If you use a particularly named style in both, the subdocument and the master, only the definitions in the master will be considered. So yes, you can later change the styles in the master without thinking about the subdocument settings. The only “surprise” you can possible find is if you use a style in the subdocument that’s not defined in the master: in that case, the style will be imported.
Got it. Thanks for your help!