Lynn
This activity is about your ability to remain at a workstation, standing at it, sitting at it or moving between the two as necessary, the clock only stops when you have to move away from the workstation in order to avoid significant discomfort or exhaustion.
As to moving from one chair to another, this is separate, there is no requirement for you to stand for 10 minutes before sitting again, in fact there is no requirement for you to stand if you could, for lack of a better description, wriggle across you will be counted as being able to move between the two chairs.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems