From:
stgeorgegoc.org/pastors-corner/wedding-marriage
"Pastoral Guidelines
For the union of a man and woman to be recognized as sacramentally valid by the Orthodox Church, these conditions must be met:
• The Sacrament of Matrimony must be celebrated by an Orthodox Priest of a canonical Orthodox jurisdiction, according to the liturgical tradition of the Orthodox Church, in a canonical Orthodox Church, and with the authorization of the diocesan Bishop." …" the Orthodox Church will bless marriages between Orthodox and non-Orthodox partners, provided that:
The non-Orthodox partner is a Christian who has been baptized, in water, in the Name of the Father and the Son and the Holy Spirit; and
The couple should be willing to baptize their children in the Orthodox Church and raise and nurture them in accordance with the Orthodox Faith. A baptized Orthodox Christian whose wedding has not been blessed by the Orthodox Church is no longer in good standing with the Church, and may not receive the Sacraments of the Church, including Holy Communion, or become a Sponsor of an Orthodox Marriage, Baptism, or Chrismation.
A non-Orthodox Christian who marries an Orthodox Christian does not thereby become a member of the Orthodox Church, and may not receive the Sacraments, including Holy Communion, or be buried by the Church, serve on the Parish Council, or vote in parish assemblies or elections. "
From:
stgeorgegoc.org/pastors-corner/communion-inter-communion
Can Orthodox Christians receive communion in the Roman Catholic Church? Can a Lutheran receive communion in our Greek Orthodox Church? These are common questions that I encounter in my ministry. It is a complex issue because of our American society where we have many different Christian denominations co-existing within our cities and towns. The simple answer, which many people may know, to the question is “no.”
Note from jt: Perhaps an Orthodox CAF member will be able to provide a link on communion issues. My understanding is that communing in the Roman Catholic church involves automatic excommunication, but I do not have a link to support this.
From:
oca.org/questions/romancatholicism/communion-in-roman-catholic-church
Communion in Roman Catholic Church
Question
"As a Greek Orthodox may I receive the sacrament of Holy Communion in a Catholic Church. Do you know the rules regarding Greek Orthodox and Catholic relations? I live in an area where the closest church is a Roman Catholic Church. Does the Catholic Church recognize us as equals?
Answer
Orthodox Christians are not permitted to receive Communion in non-Orthodox communities, including the Roman Catholic. To do so would imply a unity that in fact does not yet exist. Also it implies that we are “united” to the faith community from which we receive the Eucharist."
Should the young people find their way back to their respective faiths, how to raise the children, fulfilling Sunday obligations separately, convincing a spouse to have a civil marriage convalidated (Catholic) or blessed by the Orthodox church.
In addition, one might imagine pressure from in laws and relatives who wish to see spouses converted.