No, you can't
combine 2 different years on a tax return. If you filed your return in 2015, you will have to amend that year to add the K-1 imcome. TurboTax Online for 2015 is
no longer available, however you can still file your last years return with the
TurboTax CD/Download version. Prior
year TurboTax Products
See the TurboTax FAQ below for instructions on how to amend prior year tax returns.
https://ttlc.intuit.com/replies/3288565