Complex sentence: The 2004 convention was first postponed, then canceled altogether, although SAS later announced a joint event with the organizers of Yuricon called Onna!, held in October 2005.
Split into simpler sentences: The 2004 convention was first postponed, then canceled altogether. Working the with organizers of Yuricon, the Shoujo Arts Society later announced a joint event called Onna! which was held in October 2005.