IQFeed data on ET, how to account for DST and half hour time zone diffs?

I've confirmed with IQFeed support that "IQFeed sends all data in Eastern time. It is up to your third party software to alter that if that is a need." AmiBroker Intraday Settings has a time shift with an integer value to be entered, but how would I take data in New York time and consistently correlate it to Mumbai time, accounting for daylight savings time change each March and November, plus half hour (10:30 not 10:00) time shift?

As an example, I got 1 minute data for IN#C or the Indian Nifty 50 futures trading in Singapore.
New York EST (winter) is +10:30 hours to Mumbai, while EDT (summer) is only +9:30 hours to Mumbai, and additional 2:30 hours to Singapore.
Highest volume in December is 22:45:59 - 4:59:59 so quotes are stored in NY time, corresponds to +10:30 time zone shift or 9:15 - 15:30 Mumbai time
Highest volume in the summer, starting March 8 2020 is 23:45:59 - 5:59:59, corresponds to +9:30 time zone shift or 9:15 - 15:30 Mumbai time

Similarly to what was described in this KB I would like to compress this 1 minute data to per day quotes (daily bar = 9:15 - 15:30 Mumbai time), see it consistently in charts and run backtests against for multi-year time frames.

Sorry, but AmIBroker only supports integer timeshifts (integer hours). Half hour timeshift is not supported.