First you would have to exactly recreate the original return (is it for 2020?) in TT, then fool the system by saying you are going to file it by mail (but don't actually do so). Then come back at the end of March when the 1040-X amended return form is ready here. But I don't know if you will then be able to efile the amended return through TT since you did not efile the original return with them. You might have to file by mail.
