Yeah, not sure what
@JasSwitch7's full situation is, but sounds like Primary might have insufficient tax liability to get the full value of the credit while Secondary might both have the liability and be under the income threshold for 2023. I've seen various posts of people buying with non-jointly-filing co-owners such as siblings or parents or (non-dependent?) children, so hopefully this helps those who were trying to get the official form filled out correctly with Secondary's information (and presumably submitted to IRS).
Now in 2024 with point-of-sale and the recent change to Tesla's backend of generating Secondary registrant 15400, this could mean it's possible to get $7500 taken off the purchase price by adding a Secondary who is under the income limits. (I believe I've seen at least one post where someone "paid" an extra $250 to re-order again but switching Primary and Secondary effectively getting a $7250 credit, so presumably this won't be necessary now.)