Uh, you do KNOW that the 17th century priests of the Roman Church used to say mass for the EASTERN ORTHODOX and the Armenians in the Peloponese with the approval of both THEIR bishops and the Armenian/Greek orthodox Bishops right? And it's funny because the Armenians are in communion with the Copts.
Read the history people. Eustratios Argentis by Metropolitan Kallistos Ware.
This isn't new.
"Not only the higher authorities but the local population received the missionaries with great enthusiasm. “During the seasons of Lent and Advent”, a Jesuit priest relates, “…the preachers, on leaving the pulpit [of the Latin churches], are sometimes forced to go up again into those of the Greek and Armenian churches, to satisfy the desire which people have to hear the word of God… The missionaries often go to pay their respects to the [Greek] bishops and clergy, with whom we maintain a perfect understanding; the conversation is always on some religious topic, for several of them ask only to be instructed.” “The Greeks and the Syrians”, writes Père Besson in the middle of the seventeenth century, “open their houses to the apostolic men; they open even the doors of their churches and their pulpits. The parish priests welcome our assistance, the bishops beg us to cultivate their vineyards.”
Not only that, we SHARED Common worship!
"Instances of common worship and communicatio in sacris during the seventeenth century are so frequent that only a few examples can be mentioned here (the evidence is set forth in detail by P. Grigoriou, and by G. Hoffman in numerous articles). Some of the most striking cases are found in the Ionian Islands, at this time under Venetian rule. An anonymous Athonite monk of the sixteenth century has left a vivid description of the situation prevailing on Kerkyra (Corfu), where members of the two churches lived side by side on terms of the utmost friendship. While the monk himself disapproved strongly of what went on — he entitles his work ‘The Errors of the Corfiots, on Account of Which We Excommunicate Them’ — it is evident that on Kerkyra itself these acts of friendship were accepted as a matter of course. The Greeks, so the monk writes, receive communion from Roman priests and go to them for confession. The clergy of the two churches hold joint processions on Corpus Christi and on Holy Saturday, and even celebrate the Eucharist simultaneously in the same building, although at separate altars:
“The Latins hold a procession with the unleavened bread which they consecrate and call the Holy Gift. In front walk the Jєωs, then the Greeks, and after them the Latins — all of them together dressed up in their holy vestments; they sing together and all become one.
The Latins observe a festival in their cathedral in honor of a certain Arsenius, a local saint; and Greeks and Latins celebrate the Liturgy together in the same building, but at separate altars. The Greeks read the epistle first, and then the Latins, and the same thing happens with the Gospel. As for the people, both nations stand mixed up together in front of two altars, praying together and singing together…
On Holy Saturday the Greeks and Latins assemble in one of the Latin churches and the priests of both sides together carry upon their heads the Epitaphion or Lamb, all together carrying the same Epitaphion, and they go with it to another church.” (Athos, Iviron, ms. 1340, quoted in Grigoriou, pp. 112-13)"
You think a bishop simply sitting in on a Latin Mass is ecuмaniacal?! HA! Try living in the 17th century in Greece! You would be scandalized out of the country!