It simply shouldn't be legally possible to sign a co-author onto a work when a) the work has already been published and b) the original author/s is/are dead and didn't pen it into their Will. This just makes possible mountains of fraud with the author being unable to defend their copyright. Also the supposed "co-author" is dead. Otto isn't to lay claim to authorship. Anne didn't give him authorship. Why exactly does anyone else have the right to lay claim to this copyright?

I'm a traditionalist when it comes to copyright, and by that, I mean that I believe in the spirit of the statute of Anne of 1709.

Copyrights didn't exist before then until publishers decide to invent them out of nowhere and make them last literally forever (to line their own pockets, not to help the authors). The statute of Anne axed that by giving an exclusive monopoly for a limited period of time (14 years, extendable once by another 14 years) as a necessary evil.

The idea behind it is that a people must own its own culture and that culture should thrive. Therefore, to encourage more of that culture we give a monopoly, and to ensure ownership by the people we make it end.

These days, law makers treat the expiry of a copyright as a bug and try to work around it while it's the whole point.