Bud, I'm in the same situation. I have got HDFC Swiggy as my first card, been 4-5 months now. But they have given me a very low limit of 20k. I will ask for a LE after 6 months have been completed. I've been spending 25k/Month on it.
Similar to you... Guys here say to close my CC and then wait 3-6 months to apply for a new one. But I don't wanna give this up as I get around 1500 cashback/month. Also, it is my primary card because of such great returns for my spending.
So I have a few Questions...
1. What was your limit on HDFC Tata New when you applied for DCB?
2. Did you get DCB with a shared limit or a new limit? If new... what was it?
3. Did you have a bank account in HDFC at that time?
4. Is there anything else that I need to know about how to apply for a core CC from a cobranded one based on your experience?
Ps. I will have an SBI Elite (which will have a much higher limit than any of my CC Rn.) by the time HDFC Swiggy completes 6 months, and I might get upgraded to HDFC Classic Banking too. So, I can Apply C2C too via bank if required.