247. “Issues involving mixed marriages require particular attention. Marriages between Catholics and other baptized persons ‘have their own particular nature, but they contain numerous elements that could well be made good use of and developed, both for their intrinsic value and for the contribution that they can make to the ecumenical movement’. For this purpose, ‘an effort should be made to establish cordial cooperation between the Catholic and the non-Catholic ministers from the time that preparations begin for the marriage and the wedding ceremony’ (Familiaris Consortio, 78).
What are these good elements? One, an opportunity for a married person to share faith and to listen attentively to the experiences of the spouse. There persists a myth that subdivisions of Christianity are religions in their own right. They are not. The “mixed” marriage, in many cases, is part of that myth. Even among people who are each deeply connected to and active in different Christian traditions. More of a challenge would be one person who is very active in their church tradition, and a spouse who is far less so in their own.
As for the wedding, what about Eucharistic sharing? The synod bishops cited a 1993 Vatican document:
With regard to sharing in the Eucharist, ‘the decision as to whether the non-Catholic party of the marriage may be admitted to Eucharistic communion is to be made in keeping with the general norms existing in the matter, both for Eastern Christians and for other Christians, taking into account the particular situation of the reception of the sacrament of matrimony by two baptized Christians. Although the spouses in a mixed marriage share the sacraments of baptism and matrimony, eucharistic sharing can only be exceptional and in each case according to the stated norms’ (Pontifical Council for Promoting Christian Unity, Directory for the Application of Principles and Norms on Ecumenism, 25 March 1993, 159-160)”.(Relatio Finalis 2015, 72)
For your reference, remember that Amoris Laetitia is online here.