No one. There is no requirement for this to be done in secret, and indeed, doing it in secret makes it less likely the real owner will find you. The chances of someone tracking down the real owner via blockchain analysis is much smaller than the chance of the real owner finding you after you publish the address in a public forum such as this one.

I've had many users over the years contact me privately after I helped them out in a thread, asking for more advice or even offering to share things like scrambled seed phrases or partial private keys asking me to help them brute force them. My response is always the same - far better for both parties to keep the discussions public, so the other party can get opinions from other forum users on the things I tell them and can verify I'm not trying to scam, and so that I cannot be accused of scamming them in private.

Sharing the address does not allow anyone else to attempt to steal the coins, so you should start there. If you want to proceed to creating an OP_RETURN as has been suggested in this thread, then I or someone else can create a transaction for you which can be verified by other users so all you have to do is sign it with the private key. And again, we can publicly talk you through the steps to do that. Doing all this publicly is far safer than you sharing the private key with someone on this forum, even someone well trusted.