Encryption – How can I get a pair of ed25519 keys from a pair of secp256k1 keys?

Alice used a pair of secp256k1 keys that she had used some time ago to communicate with Bob.
Bob can no longer use secp256k1 but only uses ed25519.
Alice and Bob can not exchange any messages.

Is there a secure algorithm that Bob can use to derive a public key ed25519 from Alice's original secp256k1 public key; Alice can also derive a private key ed25519 from her original private key secp256k1