My cousin first applied for his visitor visa to canada 15 years ago in 2004 and was rejected. He re-applied in 2006 and obtained his visa. He declared 2004 visa refusal on 2006 application. 7 years later in 2013 he applied for and obtained his 10 year visitor visa. This time he is 70 and forgot to disclose 2004 visa refusal on application. In 2019 his children sponsored his PR application but he also forgot to disclose 2004 visa refusal. He now just received a letter asking him to provide an updated imm5669 background form and he suddenly recalled his 2004 visa refusal. What is his best course of action to take now? Thanks!