NRI's should not be having normal bank accounts . They should be converted to NRI accounts . Ask your family to contact local branch and get t converted to NRI account, I don't these need Adhaar card.
Yes. You can convert it to an NRO only because it’s a rupee account. Yes, you have to pay tax each year. For that reason it’s best not to maintain high balances in your NRO accounts. I don’t know if there is a way out other than maintaining a balance that doesn’t gather interest which becomes taxable. Either way, it’s always good to file taxes in India if you have bank accounts there.
I think NRO/NRE accounts need a PAN card. When converting existing account it can only be made NRO. But you can open an NRE account too, and future remittances from a foreign country can be made to this account.