I know that it is sunnah of prophet(PBUH) to make group dua and say ameen for that.
But, my question is
Is it sunnah to make group dua after Fard jamaath prayer?
In our area(Tamilnadu, India) we had a practice of asking group dua after jamaath of every fard prayer(ie, imaam will ask dua immediately after salaam). But, when I went to north India there such thing does not exists. Is it a bid'ah?