Private User - but you do have the option of asking curators to MP your profiles. And even to lock profiles that are prone to mis-merging over and over.
Right now we can revert to correct data fields easily. So that is the way to undo bad edits quickly. It is bad merges that are the worse. And there are options to prevent these - (1) use of Display Names to name individuals uniquely; (2) MP and even locking; (3) use of Display Names to add dates to prevent merges of two individuals with the same name.
If the person is in your family group, you control who you allow in the family group and who you collaborate with. I stopped collaborating with people who make bad merges and I don't allow people in the family group except family and if I were to have a family member who made bad merges over and over, I would re-consider.