Perhaps, but given that in this thread
http://www.flyertalk.com/forum/showthread.php?t=490823

there is a long discussion about DL not being able to add a OP number to a reservation, I'd say it's less doable than common sense might suggest. Then again, SkyMiles customer service might be not forwarded to India, and may be competent and responsive. Or it might be a part of Delta.