Question: Additional Content for Search Term

I try to add additional content to the index of html docs that can be searched/found via

I tried to add an additional field to the fess-index in ES. The field is filled correctly during crawling. But the field will not be searched with fess. Direct search in ES works (/fess.20171204/doc/_search?q=SEARCH_TERM) and finds all elements with SEARCH_TERM in the additional field. It seems that only the content and title field will be searched in fess. ( works, but is no alternative)

Or is it possible to add special/additional content to the content field in ES during crawling?

See copy_to.
For example, to copy the additional content to “content” field, the mapping is:

        "FIELD_NAME": {
          "type": "text",
          "copy_to": "content" 

Thank you for your help. Works very well.