Two families of Orthodox churches: is it possible to unite?

The Fourth (Chalcedonian) Ecumenical Council in 451 divided the Ecumenical Orthodoxy into two large parts. The first is Orthodox churches (Chalcedonian, orthodox, "Eastern" (Efsten), which include the four ancient patriarchates (Constantinople, Alexandria, Antioch, Jerusalem), along with the younger recognized and unrecognized autocephalous Orthodox Churches, which today are numbered around the world However, in spite of the later division of Orthodoxy with the national churches (the separation here was usually based on an administrative principle), they all represent a single church community with a common faith nnyam nature and expression of church life. The basis of the true apostolic faith they accept the first, except the Bible, and even the decision of the seven ecumenical councils.