Question about the addition of hydrogen to a molecule undergoing MoleculeModify

I would like to identify the atom that used to participate in a bond before the molecule was modified by MoleculeModify[mol, {"DeleteBond", {idx1, idx2}}].

According to the official documentation of MoleculeModify:

When removing or replacing an atom, the number of explicit hydrogen atoms may be adjusted to maintain proper valence. Disconnected hydrogen atoms will be removed.

This suggests to me that I should be able to find the formerly participating atom in the connected component by finding the current bond that features the highest atomic index (mol // AtomList // Length).

My questions are:

  1. Is the new hydrogen atom, added to balance out the valences, always guaranteed to have the highest index in the list of atoms of the connected component? (In other words, is such an approach robust?)

  2. Is there a better way to do this?