This is how bishop Hilarion explained it to Robert Moynahan.
I found this to be rather clarifying…
*"…from the very beginning of the official Catholic-Orthodox dialogue in 1980 until 2007 the list of participants remained unchanged,…
There are a number of autonomous and autocephalous Churches which, for various reasons, are not universally recognized in the Orthodox world. For example, there is the autocephalous Orthodox Church in America and the autonomous Orthodox Church of Japan: they were never invited to such dialogues because the Patriarchate of Constantinople does not recognize their current status. If the so-called Church of Estonia, which is an autonomous structure under the Patriarchate of Constantinople, should be invited, why not invite these other churches? Why, then, not invite the Ukrainian Orthodox Church, which has an autonomous status under the Moscow Patiarchate? What about the autonomous Orthodox Church of Latvia? What about the Orthodox Church of Estonia that belongs to the Moscow Patriarchate and also has an autonomous status?
If the composition of the Orthodox half of the Mixed Commission should be changed, this must be done with the consent of all Orthodox Churches. If, however, there is no such consent, it is safer to preserve the composition of the Orthodox group as it was from the beginning - until the matter is resolved at a Pan-Orthodox Council."*
Here is a little background on the Estonian church issue, an older article.
This little blurb from
Wikipedia gives an idea of the relative demographic and numerical details…
An agreement was reached in which local congregations could choose which jurisdiction to follow. The Orthodox community in Estonia, which accounts for about 14% of the total population, remains divided, with the majority of faithful (mostly ethnic Russians) remaining under Moscow. As of a government report of November 2003, about 20,000 believers (mostly ethnic Estonians) in 60 parishes are part of the autonomous church, with 150,000 faithful in 31 parishes, along with the monastic community of Pühtitsa, paying allegiance to Moscow.
There are two articles in Wiki, almost identical, one for each of the churches,
this is a link to the other article.