Dealing with a horrible database this last week, I found the need to combine things in a reasonable way. It took a lot of searching to find out how to query on multiple sets. So thought I would put it here.
var roles = (from x in userRoles from y in editUser.UserRoles where y.SOXRole && y.Id == x.RoleId select x).ToList<DBModel.UserToRoles>();
I was pretty happy with it.