Changing a private key of a public Bitcoin address I would like a way to change the private key of a public address, for this you'd of course require the current private key.
Is this at all possible?

I want to prove that it can be done, or prove that it cannot be done.
It cannot be done.

Every private key has exactly one public key, and every public key has exactly one address (ignoring compressed/uncompressed or normal vs P2SH address, which do not matter here).