If you want to travel around domestically in India with the same luggage allowance as your USA-IND flight you will need to have all those reservations on the same ticket.

Showing that you traveled to India internationally 3 weeks ago on Delta as a Diamond Medallion and therefore SpiceJet (a LCC) is obliged to give you the same luggage allowance is asking for a bit too much.

The problem with having all your reservations on the same PNR as your USA-IND flight would invariable mean a huge hike in overall cost of the ticket and it might be significantly cheaper to buy domestic sectors separately.

TLDR: International travel size/weight cannot be used at all on separate domestic tickets. You will have to purchase additional baggage allowance OR use a baggage shipping service which can be more cost effective sometimes but take more time for your bags to arrive.