Marilyn, I think you are not quite correct in your assumption about Part 4. I have recorded many 'Easy Record' songs using Technichord with Conductor, Right1, Right2 or Left selected and I can assure you that the Technichord IS recorded within the sequence, without using Part4. If you have a look in the Step Edit screen, at a song which has been recorded using Technichord on say Right1, you will see that all the harmony notes are present, together with the Melody note, in the Right1 part of the sequence. In other words, the Harmony is embedded in the selected Technichord 'Target' part - RIGHT1, RIGHT2, LEFT. If CONDUCTOR is selected, then the Harmony is embedded in the selected voice for Right Hand : RT1 selected - Harmony in Right1 : RT2 selected - Harmony in Right2 : RT1 & RT2 selected : Harmony in Right1

Part 4 can indeed be used to provide another 'Instrument' and provide the Harmony notes and in this case, the selected Right Hand voice (RT1 or RT2) would only contain the Melody notes and all the Harmony notes will be contained in Part4, using whatever instrument has been assigned to Part4. So, for instance, you could have RT1 set to Trumpet, RT2 set to Trombone and Part4 set to Alto Sax. If you select RT1 to play, turn on Technicord and set it to CONDUCTOR, then you will hear a Trumpet with Trumpet harmony, However, if you set Technichord to Part4, you will now hear Trumpet with Alto Sax harmony. Selecting RT2 voice, Technichord to CONDUCTOR you will of course hear Trombone with Trombone harmony. Changing Technichord to Part4 results in Trombone with Alto Sax harmony.

To get back to Cees original question, Part4 is automatically included in the 'Save' function of Easy Record and is the only one of the 'Parts', which is treated this way.If you have not used it as the Technicord harmony instrument track, then it will be empty.
Another use for Part4 is that it can be used to add a counter melody after you have done your 'Easy Record' sequence, using the 'Real Time Recording' function. This assumes you have not used Part4 for Technichord. The resultant recording still only uses the Six parts allocated to Easy Record.
I apologise if I am trying to tell anyone how to suck eggs

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Willum