Martin Sheen, Brad Pitt, and George Clooney headline play supporting marriage discrimination

That's right.  The story is right here. Of course I could be wrong.  Some of them may well support the right of siblings, family members, and minors to be married.  They may also be in there swinging for marriage equality for polygamists and other polyamorous people.  But my hunch is, the tired and inaccurate 'marriage equality' is here, as it usually is, applied only to marriage for homosexuals and lesbians.  They may well not have a problem advocating discrimination against those other approaches, hence they are not really for 'marriage equality'.  Like so many superficial slogans of the progressive movement, it means nothing but an attempt to shut down debate lest too many people begin to ask questions and put two and two together.