A bit of manual work, but it would be solid and fair. Then we could carry on.
You gave NXTDrop holders Ethereum NFTs without collecting the NXT assets from them, so its arguable there is no real link between them and the original project. Now you have peeps trying to sell their ETH NFTs and NXTDrop assets.
The only real NXTDrop tokens are the original assets on the NXT blockchain, as far as I'm concerned. They need to be locked on NXT for a redeemable Ethereum token ala Emblem Vault. Without something like that, you're just creating brand new NFTs.