If you have the incorrect IT203 set up in Proseries as filed, you can activate IT-201X to make the amendment. and then make whatever other changes you need to.... Income info should transfer correctly once you select correct county/school district info.   On it-201-x page 6 they as reason for amending.  Select N - Other and tell them it was incorreclty filed as IT-203.  Should be able to efile .... but w/ Proseries... one never knows.... do one? 

edit.. note... once you activate the IT-201X you have to go back to the NY info worksheet and make appropriate changes...I tried one and it seems to werk pretty well. .