Can I amend 2 years back tax return with the itin generated this year

Dear Team,

 

My daughter was not with me during the enter year of 2018, she came to the US at the end of 2019 so I applied for ITIN for her with the 2020 returns. Couple of weeks back I got the ITIN number finally. 

 

Question is, can I amend 2018 returns and claim Child tax credit of $500 with the new itin or can't I because the itin got created this year and not 2018.

 

Please let me know.

 

Thanks in advance.