FC SD VIII: 37 (what follows is the text from McCain, first edition, emphasis added) :
Many eminent ancient teachers, such as Justin, Cyprian, Augustine, Leo, Gelasius, Chrysostom, and others use this comparison [Gleichnis, similitudine; Tappert translates this as "analogy", Triglot renders it as "simile"] about the words of Christ's testament, "This is My body." Just as in Christ two distinct, unchanged natures are inseparably united [unzertrennlich vereinigt, inseparabiliter... unitae], so [also, ita] in the Holy Supper the two substances - the natural bread and Christ's true natural body - are present together here on earth in the appointed administration of the Sacrament.Tappert's translation reads: "indivisibly united."
Does this mean the authors of the Formula are accepting the "indivisible" or " inseparable" union part of the analogy between the Personal Union and the Sacramental Union? If so, then the bread and body - and the wine and blood - can no more be separated one from another by some passage of time or by a liturgical landmark than the human and divine natures can be separated in our Lord.