Agreed. Especially without tools for that purpose.
Clean Phantoms already does and ‘corrects’ them by resetting the phantom FatherID|MotherID to 0. But that does nothing to find or correct an erroneously replaced or removed parent caused by the defective drag’n’drop.
Yes. My assumption is that it began with 10.0.0 but there is a parallel in
Set Relationships & Kinship List omit descendants of person with unknown spouse! 10.0.1.0 that led to a fix in 10.0.2 in September along with * Fixed: Drag and dropping a parent to a single parent on the family view didn’t link the parent. There’s no mention of any change to drag’n’drop in 10.0.3 so the problem must have been introduced no later than September and no earlier than July last year, 5-7 mos ago.