Stimulus Check for Newly US Resident

I have an interesting case.  My client's wife became a US resident on 8/2019.  They been filing together for several years with the wife's ITIN number.  

Last year in their 2019 taxes we used her ITIN number instead of her newly Social Security number because we have had several cases with other clients the IRS holding returns for long periods of time and sometimes even denying refunds (another topic for another discussion)  when the SS is less than 6 months of the previous year.  The taxes were made before the pandemic hit so we didn't know that this disqualified them from the Stimulus checks. 

Now this year my client received the second stimulus for himself and not for his wife which we know we can claim it this year with the RRC BUT he is now asking if they are going to be able to get the first stimulus check since she DID have social security number all 2020 and 4 months of 2019.

* Will I have able to us the Recovery Rebate Credit for that first round?

* Should I make an amendment return for 2019 and THEN file 2020 taxes and apply the RRC?

or anybody has any other suggestions?  I know that amending will take time and I am not sure client will be happy.