Hi Sky,
Thanks for reaching out. With regards to your concern, Yes you can not use an advertising account for the Budget Order Service to manage payment information. You should use only whitelisted Google Ads manager accounts.
Let me know if you have any questions.
Thanks,
Nirmita Patel Google Ads Team
Hi Sky,
Thanks for reaching out. With regards to your concern, you can change and edit budget info via API. But you needs to have a whitelisted MCC account that is linked to your account to make the changes. You can't just make changes just cause you used to have a whitelisted MCC account that is not connected anymore.
Thanks,
Nirmita Patel Google Ads Team