Thanks Alec and Rog.
Let us suppose I have a good midi backing tune that I want to use. I save it as a Technics GM2 file and mute the lead, e.g. .

I load the file and play the lead with R1 and Left hand.

The problem only comes up when I jump to the next number to load, and it is an arranger registration. I forget occasionally to turn off the sequencer play button before I load the next song. The registration doesn't load. The same previous one is still in the sequencer.

The other question was how to record a melody I play , along with a midi converted to Technics.

I am sorry for the confusion caused by working on two questions at the same time.