third stimulus check --how to get the rebate on 2020 return

We are married filing jointly. We didn't have enough income to file in 2019.  

we received the first and second economic stimulus checks of $600 x 2 = $1200 and then $1200 x 2 = $2400 however for the third stimulus check, we only received one $600 check.  We were told by the IRS that if we submitted our 2020 Federal return, that we would be made whole and that the additional $600 for the other person would be automatically applied when the return was calculated.  I am in Turbo Tax Premier and getting ready to submit it, however it is not calculating that the additional $600 is due to us -- in fact, Turbo Tax is indicating that the third stimulus check will be applied on the 2021 tax return...however we won't be required to file a return in 2021 based on our expected income.  Is there some way to get this third rebate credit applied to the 2020 tax return that we are about to file for the October 15, 2020 deadline?