Marriage Banns

Peter Tatchell, of the campaign group, OutRage! has begun a campaign for marriage or civil partnerships to be available to all.

"Civil marriages and civil partnerships should be open to everyone without discrimination."

At the moment this demand seems to be set in the context of same-gender couples being able to marry, and different gender couples being able to civilly partner (there doesn't seem to be a suitable verb). Marriage is a much more far-reaching and structurally-important institution in our society than is civil partnership.

Subrosa has a fine post, and many comments from differing viewpoints,  on this topic.  What though does this campaign want precisely?  There have been arguments, for instance, that civil partnerships should be extended to co-habiting siblings.  It would be wholly outside of our cultural mores if such an extension were pressed after civil partnerships and marriage had been made interchangeable. At the moment many do not want gender to be a constraint upon one or the other.  What about degrees of kinship?