Hello Bluegoat,
The only time when the Catholic Church says a recipient does not need to have some intention to receive a Sacrament is when the person is unable to form an intention–in other words, infants. For any adult who *can *form an intention, such an intention is necessary for validity. There was another thread on this topic several months ago. Not that I am the final authority on this, but I said more about the topic there.
forums.catholic-questions.org/showthread.php?t=546291
Regarding marriage: if a couple has an intention contrary to the nature of marriage at the time they exchange consent, that marriage is invalid. If they, later on, change and have proper intentions, the marriage becomes valid. The most obvious example would involve children/openness to life. For example, a couple might have a positive intention to deny each other the right to natural relations/children. Later on, let’s say they freely decide to have natural relations and would accept a child. They have validated their marriage by now expressing, in action, their proper consent. This is expressed in canon law, in c. 1159.1
vatican.va/archive/ENG1104/__P46.HTM
Such a validation is impossible for the other Sacraments since the recipients are not the ministers, as they are in marriage.
Making vows in a religious order is not a Sacrament. So, I am not sure what you mean by mentioning that.
To the OP: if such a person has an intention that is truly contrary to receiving the Sacrament, or never had any intention whatsoever to receive it, it will not be valid. Most kids that age might do it just because Mom and Dad want him to but this is not really a contrary intention. It is a motivation, not an intention. So, as far as validity goes, I’d say all these Confirmations are valid. But, the full effect of the grace of the Sacrament might be dormant until the kid decides to actively receive/utilize it. This is not canon law, though, so I’m out of my element with this comment.
Dan