I do know between the Alexandrian Greek and Coptic churches, either Church is fine to take communion in (or any of the sacraments for that matter). The only issue is that it will probably be recommended to stick to one Church. But at a grassroots level, the unity of the Orthodox churches of Alexandria seem to be deep-rooted in marriage. Just think about it, if every Copt was to marry every Greek, we would be united already.
But seriously, I would suppose by that example, the bishops would agree that either church will openly give the Eucharist, but would advise strongly against Church "hopping" or splitting the family into two churches. It's better that the whole family is united in all things and decisions. But I don't think there's a problem for "visiting" the "other" church once in a while and partaking of the sacraments there as well.
God bless.