For words that only have three letters, there is absolutely no 4th letter. One example is with the word “include”, there are no more letters Later on and thus need to be the word "insert". The word “addict” is within the BIP39 wordlist however , you would've used “addi” for https://open.substack.com/pub/jaidenqrel955/p/unlocking-the-power-of-bip39-how?r=54uq0h&utm_campaign=post&utm_medium=web&showWelcomeOnShare=true