You do not include the transactions that occurred after her death on her tax return. Reporting them on the 1041 using the step up in basis is the proper way to handle the transactions. If you want to e-file your aunt's return, you can report summary totals for any transactions that need to be reported, and then send your statement along with Form 8453 and copies of the 1099-B. That way you want have to print and mail the entire return.
