Bip39 passphrase wallet https://collinmmss433.lucialpiazzale.com/from-concept-to-fact-generating-bitcoin-addresses-with-bip39 While it takes advantage of BIP32 method you can even now import BIP39 seeds into Electrum wallet. Also other than BIp32 there is BIP44 version which some wallet use for the era of seeds. For words that only have 3 letters, there is no 4th letter. https://royalbookmarking.com/story20453028/bip-39-pdf-bip39-compatible-wallet-options-https-x-com-tundra838554