"Invalid Entropy" when using Mnemonic password derived seed as entropy for new Mnemonic about bip39

[dcousens]

@lacksfish, please see BIP39

The length of the derived key is 512 bits (= 64 bytes).

The derived key is seedFromFirstMnemonic.
You are providing greater than 32 bytes of entropy to entropyToMnemonic, which the strict rules are that 128 <= ENT <= 256.

If you see this being done elsewhere, they are probably not adhering to the standard as strictly.

[lacksfish]

Can you then by any chance share the code snippet using bip39.js to derive a mnemonic from another mnemonic given a password as described by the initial BIP39 spec?

I'd really would like to learn more about the plausible-deniability this BIP39 feature offers and I am confused given this functionality seems to be differentiating amongst BIP39 implementations.