The IRS can't detect
the absence of these forms
at filing, but will likely catch them later on down the road, when you'd face not only the
additional tax liability, but also penalties and interest.
So, unfortunately,
you'll need to amend your return.
Please see the
TurboTax FAQ "How to amend (change or
correct) a return you already filed," below, for instruction on how
to amend your previously-filed tax return.
https://ttlc.intuit.com/replies/3288565