Frats and Sororities combining?

I know a year or two ago it was the case that if half the members of a frat wanted to join a sorority, they could as long as half the members of the sorority agreed to join the frat. Like, an even exchange. The only rules were boys had to stay in the rooms with other boys, and no boys could be in the bathroom while girls were pinching a loaf. Is this still true? Thanks!