Policy #2: non-sacramental sharing:
Further, given the same principles, common participation by Catholics with their Eastern separated brethren in sacred functions, things and places is allowed for a just cause.(Agitur de s. d. communicatione in sacris extrasacramentali, Concilium est quod mitigationem concedit, servatis servandis.)
What might constitute a “just cause” in the experience of anyone involved in an East/West mingling? Remember that the issue of ecumenism with other Western traditions will be upcoming in our next Vatican II document.