For words that only have 3 letters, there is absolutely no 4th letter. As an example with the word “include”, there won't be any a lot more letters Later on and thus need to be the word "include". The word “addict” is during the BIP39 wordlist but you might have https://tornadosocial.com/story4314340/detailed-notes-on-copyright-wallet-seed-phrase-out-of-bip39