You cannot just add direct deposit information to a filed return. The IRS would not get the banking information. The IRS is going to give taxpayers the chance to enter their own banking information. See the following:
The IRS does not have my direct deposit information. What can I do?
In the coming weeks, Treasury plans to develop a web-based portal for individuals to provide their banking information to the IRS online, so that individuals can receive payments immediately as opposed to checks in the mail.
https://www.irs.gov/newsroom/economic-impact-payments-what-you-need-to-know
