Duplex and gray scale printing using CUPS API

[Azuri]

I can modify the PPD file and do it,but I want to do it through API. My application uses generic PPD but when user selects Duplex option in my app, I want to add duplex option to printer before it gets added to the system. Is there an api to do this? Please let me know.

> I am using genric PPD file in my code to add a printer using cups. What api's should I use to allow grayscale printing n duplex printing. I do see some PPD API's but cant get the correct flow of using them