Can I send this second edition for free to every address who already have the first edition?
NO. If you like, you can send the book to anyone you like, but you can not send the token you have sold to someone before to another person unless you have access to the private key of the wallet the buyer use to buy the token. i think the only way is creating new NFT correct me if i am wrong and send them to your user and if they still have the old book they can send to burn address 
Yes, I'm aware of that, you will receive the corrected version and also keep the original one. But thanks to your answer now I realize about another problem: a person paid for "one" but got "two" (the original and the corrected version), and can sold the first one.
You might want to look at scripting a smart contract for an airdrop or an ico as this is likely what this is.
The airdrop version of this, would charge you to distribute the nft.
And ico reclaim style system would charge the owners the transaction fees for the new nft.
Both would require some parsing either by the chain or by you to work out who holds the nft. Also if nfts are transferable, have you thought about who owns the copy if they are transferred?
The airdrop version of this, would charge you to distribute the nft.
And ico reclaim style system would charge the owners the transaction fees for the new nft.
Both would require some parsing either by the chain or by you to work out who holds the nft. Also if nfts are transferable, have you thought about who owns the copy if they are transferred?
The owner is the current owner, of course. If you buy an NFT and then sold it, the new owners got the right over the property of the NFT, same as a car or house.
Comparing it to an airdrop may work, but as you said, the contract must send the second NFT to the current owners of the first NFT. This is completely possible, but I'm afraid it is outside of my programming skills and I would need to hire a programmer.
Can't you just e-mail them? It is free and fast.
An airdrop or something like that will cost you.
I think people are overthinking the blockchain. Especially with those new concepts.
"I have a solution, NFT. Let's see how can I fit this solution for my problems"
It is the other way around. You have a problem, you need to find a solution to fix it, not find a problem that fits your solution
Of course, but it lost the purpose of the NFT. If a client buy a book as an NFT as proof of ownership, he will be "owner" of the first version, but would have no proof about the second one sent by email.
Anyway, your input made me find another simple solution:
Cause the current NFTs relies on an URL which points to the file hosted somewhere else (not in the blockchain), then:
Then sell the NFT normally.
The link to the actual file MUST NOT point to the IPFS network (or any other decentralized web) but to a private hosting.
When I update the file, I just replace the actual file from the host, and the NFT owner always have access to the newest file.
