I dont know maybe im wrong but i didnt find a way to “render selection to sample” and set destination to existing instruments free sample slot. I think it would be quite useful feature…
I did also noticed this. I have copied and pasted the samples afterwards to the corresponding sample slots. The “render selection to sample” function always creates a new instrument.
I’ve never used it myself as of yet, but I would of hoped it went to the currently selected slot (in which case Undo would have to work with it incase you have a used slot selected.)