No, they weren't. But then, do you really think that Rob and Doug had a 25 year plan in mind for Red Dwarf when they wrote The End? Do you think they sat writing the scene where Lister bemoans never having asked out Kochanski thinking "well this is going to make us look foolish when we have him talk about being dumped by her a few series later"? Of course not. They didn't have any long term plan, they didn't even care about continuity from one series to another, they were making it up as they went along and there's no evidence to suggest that Rob Grant wouldn't have fully approved of Dungo being Rimmer's father. So again, what's the issue here? It's not as if we've seen the subversion of some Grant Naylor masterplan. Rob's main plan while working on Red Dwarf seems to have consisted of thinking about what he might do next. He was never in it for the long haul like Doug Naylor was. I'm therefore perfectly happy for Doug to shape his universe however he likes and I don't regard the Dungo thing as being anymore canon shattering than Rimmer getting his hard light drive (did that ruin Bodyswap for anyone?). It's just a way to evolve the character.