Not sure about the limit and shared limits. But HDFC will definitely approve 3rd card. My brother hold 5 cards in total. (1 Core + 4 Co branded (Indigo XL, Tata Neu Infinity, Mariott Bonvoy & Swiggy Card))
My brother hold 5 cards in total. (1 Core + 4 Co branded (Indigo XL, Tata Neu Infinity, Mariott Bonvoy & Swiggy Card))