I would like to offer my users the ability to select ‘related articles’ for an existing article. I’ve setup a structure field, where each entry has only a single page field. This field should hold the uri of the related article, and the user should be able to add as many related articles as they should.
It’s all working fine, except that the user is not only able to add article pages to the list: they can add any page to the list, which is not desirable. I need to be able to restrict the allowed options, so they can only enter an article.
This is easy to do using a select field, but as there will be hundreds of articles in the site, a dropdown menu is not an appropriate interface choice: an autocomplete field - like the page field - is a much better choice.
So, is there a way to ‘filter’ the allowable options in a page field? Is there perhaps another solution I haven’t thought of, or will I have to use a select field?.. 
Any guidance will be greatly appreciated.