For words that only have three letters, there is absolutely no 4th letter. For instance with the word “increase”, there won't be any more letters Later on and thus need to be the word "incorporate". The word “addict” is from the BIP39 wordlist however you might have utilised “addi” for https://www.creativelive.com/student/chris-mccarthy-26?via=accounts-freeform_2