Complex indexing with multiple information layers

Hello everybody,
I am creating an index for a report based on the GRI standards. Since I am relatively new to the field of complex content indexes, I need some help.

Within a chapter, I need to identify if a headline with the coding "GRI-(number)" is mentioned. These need to be listed in the index under the headline, as well as the page number range of the chapter. (See sceenshot. I hope it is explained understandably). Inside the index, the GRIs and page numbers should also link to the specific area. 

So far I have created this manually, but since everything must also be linked correctly, an automated solution would be the better one. Can this be solved with Indesign? I have already searched for scripts and external programs, but have not found a fitting solution.