It was a little more complicated than that (it had to be!!). There is a difference between temporary commissions and temporary ranks. The former were indeed the commissions granted to non-regular officers. Whatever rank they then held, they were still holding a temporary commission which, broadly, was for the duration of the war.
However, tying down the distinction between temporary and acting rank is like nailing jelly to a wall. It altered during the Great War with some evidence that acting became more prevalent in 1915. Others far more versed in these matters than I (including MPs - see Hansard in 1915 for example
https://api.parliament.uk/historic-hansard/commons/1915/apr/22/army-estimates-1915-16-progress-10th ) have discussed the subject ad nauseam. It is fraught with difficulty and, as Regorian implies, even if explained doesn't make sense the next day!
Any attempt to explain it definitively would have to be accompanied by the relevant Army Orders of the time under discussion.
The question really was - what were their duties - answer - no different from a substantive captain whose place they had taken for some period of time.
Dora - you may wish to look at the title of the regiment. I suspect it is King's Royal Rifle Corps although there are a couple of King's Own somethings they don't have Rifles in the title.
MaxD
