I just read somewhere that the characters of Phoebe and Chandler were only suppose to be recurring, but eventually added to main status. Anybody know if this is true?

http://26.media.tumblr.com/YfSOiqBBzoatrcbgme5X74dno1_500.jpg

It's true. On one of the seasons the creators talk about casting and said that both characters were supposed to be secondary but they played them so well that the show became an ensemble.