I was able to seamlessly upgrade my dad's Premier Miles card to a Prestige card with just a single call.
They didn't ask for proof of income, possibly because he has had this card thru its many iterations, starting from when it was the Gold JCCC.
He doesn't travel much so the loyalty program status upgrades aren't of much use to him. Has anyone had any success in getting Citi to agree to award this status to an add on card holder?