Not within the terms and conditions of the offers.
The Chase BA Visa offer includes the phrase "Cardholder must travel to qualify for the 10% discount" and the AARP offer states "Customer must be an AARP member or must travel with an AARP member to be eligible for this exclusive offer".
You might be able to trick the system into letting you book what you want, but there would be at least some risk of your friend not being able to travel.
I have purchased several tickets for friends using both of these discounts, with no problems arising at time of travel.
Just last week, I used the AARP portal for a friend, and then applied the Chase 10% discount code. Both worked.
Nothing ventured, nothing gained.