I am trying to create an incremental search in my website where each searched term is added to the previous searched terms. I found that using a single search input for that confuses users. They expect that each search resets the searched terms instead of adding them to a list.
I found that Google Trends does the same thing I want to do, but using two search inputs. One big general search input that resets the searched terms and one small "Add Term" field. I like this approach more than the one I am doing.
Since Google Trends is the only site I know that is using this approach, is this the best way to perform an incremental search or there are other ways? Are there any other examples of searches like this?