I am using feed instead of share, because the properties that I will share (title, content etc) is being fetched from server with a different http call on the page. So I have used feed in order to give the parameters when the http call ended. I have used FB.ui
I want to change the sharer, actually I want to make people choose the sharer on the feed box. As I have seen from the doc, there is no comment indicates that I can change the sharer.