You're right. I don't think they ask for an SSN, which would seem to be a prerequisite for reporting. I'll let you know.
Some minor progress. As it turns out, I didn't have a ton of options as far as long-standing cards go.
My original, classic Discover card is circa 2000. I had lowered the CL to 500, as I want to keep it but don't use it (trading the CL for my MilesIt card); my wife's card is even older and we use that for any bonuses and typically don't go into card #2. So, as reported above, I added my son here as an AU. This won't add anything realistic to his total CL, but the age of the card should help.
Note that Discover asked for his SSN and a home address, while stating that the card will be sent to ME. Perfect.
My oldest cards with a decent CL are with Chase. These are nowhere near as old ... I'm betting 5-6 years old max. Still will lengthen his overall history, and the ~50k CL should help.
I may have screwed up a little here. The 2 cards I added him to total 50k CL, right? Nervous a bit, I had them sent to my home address; there was only ONE address slot. The problem might be with them connecting these to his real credit report, as he DOESN'T live here and they did NOT ask for an SSN. I may go see if I can fix this, but it may be too late.
Another fact: Chase says right on the page for adding an AU that the card will be reported to the recipient's credit report AS an AU user and may affect their credit score. Not sure of the technicalities, but it sounded like what I wanted
. There's still that address issue ... I wish I would have pre-thought a couple of minutes more.
3 cards in one shot. I'll monitor his vitals and see what happens, if anything. And I will report back in!