I don't see this in your doctrine. Where would this be in OPC doctrine/ Westminster Confession of Faith?
Here’s the deal Roman Catholics don’t understand because their church has blinded them.
When a belief, practice or article of faith is explicitly taught in Scripture, it is incumbent for the Christian to follow that belief, practice or article of faith.
When not specifically spelled out in Scripture, the Christian has the liberty of conscience to follow that conscience.
Scripture does not clearly spell out the fate of babies who die in infancy. Therefore, we look to the rest of Scripture to formulate an opinion. And it’s just that. An opinion.
I’m content to believe babies who die in infancy go to heaven. I can certainly understand the alternate view that some may go to heaven and others might not.
But Scripture is very clear that there is no such thing as Limbo. Limbo is a figment of Rome’s over-active imagination. It is flagrantly false. It is a lie. And it leads to other errors.