As it says on the About page (https://ooh.directory/about/):
> Some blogs appear in two or, occasionally, three categories. If it would take more than that, it ends up in the wonderland of Uncategorizable.
> Some blogs appear in two or, occasionally, three categories. If it would take more than that, it ends up in the wonderland of Uncategorizable.
Since there's no way to select multiple categories in the "suggest" form, I take it you will manually amend the entry.