Unlike the PIP approach where the number of inputs is strictly given by the number of internuclear distances, we are unaware of a criterion to specify the number of PIPs or FIs to be used as inputs for PIP/FI-NN appraoches, nor is this discussed in detail in papers using the PIP/FI-NN approach. However, it is clear that the number of PIPs or FIs grows significantly with molecule size. We do note that the fragmentation approach 26 for PIPs could also be applied to PIP/FI-NN approaches and so this may be one way forward for these methods, as noted in that paper.