Determining Biddah
What about the sunnah of shiites, where the chains meet all the way to sahaba ( especially hazrat Ali)?
In Shia Fiqh, Their Imam is ” Innocent (masoom) ” and has the divine authority w.r.t interpretation of religious directives which to them is equal to a source of religion. As far as basic Sunnah are concerned, there’s no such difference. The differences are in certain interpretations of Quranic directives and akhbar-i-ahad which to them is a divine directive as long as their chain of transmission goes to any of their imam to the top.