CathInfo.com

1) Can you provide magisterial sources declaring schismatic infants are members of the visible Church?

2) Can you provide magisterial sources declaring schismatic children forfeit grace at the age of reason?

If any one saith, that little children, for that they have not actual faith, are not, after having received baptism, to be reckoned amongst the faithful; and that, for this cause, they are to be rebaptized when they have attained to years of discretion; or, that it is better that the baptism of such be omitted, than that, while not believing by their own act, they should be bapized in the faith alone of the Church; let him be anathema.

Wherefore, as appears from what has been said, Christ instituted in the Church a living, authoritative and permanent Magisterium, which by His own power He strengthened, by the Spirit of truth He taught, and by miracles confirmed. He willed and ordered, under the gravest penalties, that its teachings should be received as if they were His own. As often, therefore, as it is declared on the authority of this teaching that this or that is contained in the deposit of divine revelation, it must be believed by every one as true. If it could in any way be false, an evident contradiction follows; for then God Himself would be the author of error in man. “Lord, if we be in error, we are being deceived by Thee” (Richardus de S. Victore, De Trin., lib. i., cap. 2). In this wise, all cause for doubting being removed, can it be lawful for anyone to reject any one of those truths without by the very fact falling into heresy? without separating himself from the Church? – without repudiating in one sweeping act the whole of Christian teaching? For such is the nature of faith that nothing can be more absurd than to accept some things and reject others. Faith, as the Church teaches, is “that supernatural virtue by which, through the help of God and through the assistance of His grace, we believe what he has revealed to be true, not on account of the intrinsic truth perceived by the natural light of reason, but because of the authority of God Himself, the Revealer, who can neither deceive nor be deceived” (Conc. Vat., Sess. iii., cap. 3). If then it be certain that anything is revealed by God, and this is not believed, then nothing whatever is believed by divine Faith: for what the Apostle St. James judges to be the effect of a moral delinquency, the same is to be said of an erroneous opinion in the matter of faith. “Whosoever shall offend in one point, is become guilty of all” (Ep. James ii., 10). Nay, it applies with greater force to an erroneous opinion. For it can be said with less truth that every law is violated by one who commits a single sin, since it may be that he only virtually despises the majesty of God the Legislator. But he who dissents even in one point from divinely revealed truth absolutely rejects all faith, since he thereby refuses to honour God as the supreme truth and the formal motive of faith.

I'll try to find sources for these, but it's basic theology.  Who someone has been baptized by doesn't particularly matter.  I can be baptized by some atheist and that still makes me a member of the Church.  Simply because I'm baptized by some Orthodox priest doesn't make me Orthodox.  Valid Baptism if valid Baptism and it makes someone an infant a member of the Church, regardless of the minister who conferred it.  This is Salza's error of making membership in the Church purely material.  So the infant who's baptized by an Orthodox priest is in no different condition than an infant who's baptized by a Catholic priest.  Neither one of them actively professes the Catholic faith yet ... having not yet reached the age of reason.  But their supernatural virtue of faith is infused.  But once they reach the age of reason, profession of the Catholic faith and submission to the Holy See are additional requirements for membership in the Church.  To say otherwise would have it that no unbaptized infant would be a member of the Church.