I have a client who is filing tax returns for 2020,2021,2022,2023. The first 2 years show a refund due to failure to receive stimulus payment. Although it's too late to receive the 2020 refund, the 2021 refund will cover the past due amounts from 2022 and 2023. My question is:  Would it be better to just mail all 4 years together or mail the 2020-21 and wait for filing to reopen and e-file 2022 and 2023? 

Thanks for your advice.