You're right about if the merges are all proposed or set as unmerged matches they probably won't fall trough the cracks, but indeed if for whatever reason, someone that doesn't understand why profiles are set as unmerged match, or why a merge was proposed, decides to just reject or remove all connections between the elder generations or just a few of them, it will or could be...
In this case the merge was proposed for the father, and only the father was duplicated so it wasn't a major issue, but still, even if the merge for the younger ones was approved, there automatically would pop up a warning if you would try to merge them, that would say the duplicate fathers need to be compared and or merged before you can proceed and merge the sons.
Well hope it all wil be solved soon now, good luck and thanks !