make_instr_persistent for function/group select

Assuming I have a callback for switches selecting a sample group.

If I was to switch samples/groups how do I keep this persistent if the script is reset (panic reset)?

Below is a snippet of what I am doing (as an example)

function callback
 set_control_par(%ID[$original],$CONTROL_PAR_VALUE,0)
 set_control_par(%ID[$selected],$CONTROL_PAR_VALUE,1)
 $original := $selected
 end function

on ui_control($switch)
  $selected:= 0
  $group := 0
  call callback
  end on

on persistence_changed
  call callback
  end on

I'm allowing and disallowing 'on note'

Any pointers appreciated :)

Thank you