The reason why you're not 'supposed' to buy the babies is likely because of corporate (familial?) espionage and contract law. A baby is too young to honor an exclusivity clause or an NDA even if a baby could sign one or have a guardian sign one. So technically they are a security risk.
The protocol is probably, you offer the baby for sale for an exorbitant price.
If someone actually bids on the baby, you're 'supposed' to raise the price until they quit.
But if the other party does not quit, maybe because they believe they are rich enough to deter the consequences, you actually are expected to sell the baby and sign over their employment to the other party.
(The baby is considered both property AND employed by the patriarch of the family that birthed it. This is to avoid the stigma of unemployment.)
The baby can't be terminated by its original family during its sale, as that would immediately devalue the transaction. The same way that you can't rip up documents that validate a racehorse or an expensive painting's authenticity when you sell it. You sold it for a price based on an officiated document or in this case, a record of potential value to the employer. Any involuntary termination or gap in employment mars its value. The baby's employment therefore must be transferred as if they were part of a merger.
The baby by themselves can't ratify this change to its contract either, but external parties require any change in total number of employees to be validated and reported. The new baby 'owners' could be sued for under-valuing their operation to report greater profits. So, some form of legal proxy representing the baby must accompany it to vouch for the situation-- usually the mother. And as a proxy shares the baby's status (you want to buy them as one commodity, or else your problems double!) they are also subject to the same ambiguous legal situation. And unlike a baby, they understand how to steal things.
So not only do the baby's parents make out like bandits but if they understood the situation, they now have an agent inside another business entity that cannot be held accountable or litigated against without revealing the buyer is at-fault (the seller is never at fault) for the incomplete status of their acquisition. You could just imprison the security threat, but the original family can then clean you out for abuse of what is still technically their employees.
It comes down to how long the patriarch of the baby's family can legally obstruct proceedings to maintain the maximum advantage, and how long the foolish buyer can tolerate being robbed before they have to fire the baby.
But because the transfer of employment was never correctly executed, the baby is not actually theirs to terminate, like a normal employee. The only option to get rid of the baby without even more chaos is... to sell it back for even more money. Or sell their business, which would immediately resolve the conflict.
This leaves the baby with a good start to their resume.