Include more data on an PageData object

Hi,

First, I'm not using PageTypeBuilder in this project, but maybe I'm gonna add that for some specific page types.

Alot of the web pages are a collection of other pages, e.g. teaser pages and more specific in this case tabs.

Now I'm using the PageIndexer and sets some conventions, like;

PageIndexer.Instance.Conventions.ForInstancesOf<PageData>()
    .ShouldIndex(page =>
        PageTypesToIndex.Contains(page.PageTypeID) &&
        page["ExcludePageInSearch"] == null);

But how do I include more data to the pages, like tabs and teasers? The client class has IncludeField, so I tried that;

IClient client = Client.CreateFromConfig();
client.Conventions.ForInstancesOf<PageData>()
    .IncludeField(page => page.GetExtraContent());

GetExtraContent() is an extension method which loops through all tab pages and generates a string of all content. But the content this methods returns is not searchable. I can't see the content in 'Explore Index' either.

How can I add more content to an PageData so it's searchable?