Articleship in big 4

                      hi friends, i have started my articleship in one of the big 4 in march 2013.now i found that big 4's take interns through their affiliates only as they are companies they can't take articles.in my case,i have been taken as article under some localised ca firm.however i m doing work 100% for the big 4.now i want to ask if whether it makes difference or not?and whether i can write in my resume after completing ca that i have done articleship from big4?and what may be the reason for taking articles as such?.please advise i m feeling like being cheated or is there anyone who has also faced the same situatiion?............please reply.thanks