I'll keep in mind. @Asmecher
the problem is precisely that, we need to add the 'Contributor' as new Author, furthermore, we need that this new 'Role' let us import data from an XML with importExport routine. So, trying to go deep inside the source code, there's no way for us to redefine this. At first instance, we've thinking in add some new boolean to mark a co-author(contributor) inside the author table, but as you already know, author has several tables (this is because the administrators from the GUI, want to add new co-authors). But at second instance, there's a trouble with importing data, because there's a huge XML with files associated, and there're co-authors (contributors) too. And the problem with stakeholders, is that they doesn't wat to treat those contributors as authors, are like 'reporters' from a journal.
So, since we're going deep trying to do this, there's a big issue, and we're trying to calculate how much time we need to end this succesfully. Because the great task of importing data that our friendly Software Developer Sergio Alcalá have done, take around a year. Since there where several tasks, from administrative to develop, and documentalist. By the way check this great work at URL: http://www.revistadelauniversidad.unam.mx/historico.php?dcd=2000