How do I add information on long term care income on my 2020 tax return that has not been filed yet? I printed it out to file by mail but I haven't mailed it yet.

I neglected to add the information on the 1099-LTC. I downloaded form 8853 and Schedule 1 from the IRS website. I have to file by mail since I also need to include form 1310. I'd just like to do all this in turbotax so I know it's correct and then reprint and mail. Is it possible to open the electronic process again?