Examine fluent API: grouping boolean operations

Hi all,

I'm trying to tweak an Examine search query and for this I'm using the fluent API. I'm close to a solution but there is just one thing I can't get my head around.

I'm using the code below to split the user's search query into seperate terms and since I have multiple indexed fields I'm using the GroupedOr method to create the search criteria.

            var searchTerms = searchQuery.Split(' ');
            foreach (string term in searchTerms)
            {
                if (!String.IsNullOrEmpty(term))
                {
                    if (termQueries == null)
                        termQueries = searcher.CreateSearchCriteria()
                            .GroupedOr(searchFields, term.Escape().Value.MultipleCharacterWildcard());
                    else
                        termQueries = termQueries.Or()
                            .GroupedOr(searchFields, term.Escape().Value.MultipleCharacterWildcard());
                }
            }

This would result in the following Lucene query:

+(bodyText:hello* message:hello*) (bodyText:world* message:world*) ...

As you can see the first group is required (+) and the second group is optional (or). The query I'm trying to create however should leave both groups optional, but at least 1 group is required, like so:

+((bodyText:hello* message:hello*) (bodyText:world* message:world*)) ...

Any ideas how this can be accomplished using the fluent API?

Grtz