On an AA all partner award you can NOT have a stopover in DEL.

On an AA Explorer award (mileage based) you can stop as many times as you have connecting flights. However, you must use ONLY OneWorld members and use at least two (not counting AA). And the mileage point costs are almost certainly going to be higher than the all partner award.

Given flight costs in India, it might be simpler to pay $$ for the DEL-VNS flight on 9W.

Happy wandering

Fred