Hmm if you look at where the plier head is inside the handle you'll notice that at one side there is a larger gap, the file needs to sit in the larger gap, the thin gap is slightly too thin i think. They are also of a different thickness which probably means a washer will be needed, but it would need the tab to stop the clumping like the rest of the washers. You may be able to rearrange the whole tool load to fit it in but i can't say without taking mine back apart and its just been packed up
You'll be able to fit it in, but you may have to do a bit of trial and error