No. a 2019 tax document can only be entered on a 2019 tax return. You cannot add it to your 2020 tax return. If it will make a difference to the results of your 2019 return then you may amend your 2019 return.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**