I’m not so sure if the Church has an official position on brothers of Jesus, but I’m pretty sure that since the official position is that Mary remained a virgin even after his birth that Jesus had no brothers or sisters.

We have an article on this site about it: http://www.aboutcatholics.com/faith_bel … ers_jesus/

I don’t know if Joseph was married previously. I do not believe there is any historical record of whether he was or not so there is only speculation that he was a widower since he was believed to be much older than Mary.