Isn't most of the Bulgarian Church Old Calendar anyway (I know nearly all of it, or perhaps all of it is in the US)? Why not just enter into communion with us?

In Christ,
Andrew
The Bulgarian Patriarchate is New Calendar. There are just several Old Calendar parishes in Bulgaria who are part of the canonical Bulgarian Orthodox Church (although I have no idea where in Bulgaria they are actually). All Bulgarian parishes in Western and Central Europe are also New Calendar. As for the USA, I think the convert parishes tend to be Old Calendar, while the Bulgarian ones - New Calendar.
BTW isn't the Bulgarian Alternative Synod New Calendar too? They schismed many years after the calendar switching.
Yes, it is. The Calendar was not the reason for this schism. It happened after the fall of the communism, about 20 years ago. Nowadays the Bulgarian Orthodox Church - Alternative Synod has only a few parishes. I think most parishes and priests returned to the canonical Bulgarian Church in 2002.
Last year (or in 2009) a group joined the Old Calendar Metropolitan Angelos in Greece, AFAIK they are quite a few also. Their Bishop in Bulgaria Damaskin is or used to be a scandalous person.
The largest Bulgarian Old Calendar group is the Bulgarian Old Calendar Orthodox Church which is in communion with Metropolitan Cyprian's Synod in Resistance in Greece and in the 90's was in communion with the ROCOR.
In addition there are 2-3 parishes which are under the omophorion of Archbishop Gregory of Denver.