What is the minimum credit score required for premium credit cards in India?

On the add-on card: yes, the primary cardholder is fully liable for all spends on the add-on. There is no separate credit limit or statement. So only issue it to someone you trust absolutely — spouse, parents. Not friends, not siblings you have money disputes with.

Two things nobody tells you: (1) GST is charged on the annual fee, so a ₹1,000 fee becomes ₹1,180. (2) Reward points usually have an expiry of 2-3 years. Set a calendar reminder to redeem before they lapse.