Turbo Tax messages

Could Turbo Tax come up with some way to include a message to the IRS while filing my tax returns?  I had to put in a made up number for "Cost basis" since Turbo Tax will NOT allow you to file until you fill in every last bit!  Never mind that I was unable to get this stupid "cost basis" (also called "step up") despite spending hours online doing searches, and in correspondence with my brokerage, Ameriprise.  (Even so-called "historical" data only goes back one year.)  Totally wasted at least 6 hours...

 

My message to the IRS must now be snail-mailed, completely separate from my tax return.