Get your taxes done using TurboTax
If you're using TurboTax Online, you can save your PDF from Marcus/Goldman Sachs to your desktop and attach it to your return.
You may want to aggregate your total interest/dividends from them and manually enter it as one entry in the appropriate section, and use the PDF attachment for 1099-B data. Choose Sales Section Totals.
In TurboTax Desktop, here's How to Enter a Summary in Lieu of Individual Transactions. You may not be required to mail anything, depending on transaction types.
