[SPOILER] Alexander von Brennenburg...

[charuchii]

It's possible. Amnesia took place in 1839, so there is sixty years between a machine for pigs and the dark descent. We know when Daniel went to Algeria, Hazel was 15. The average age of marriage during the Victorian age was 21, so let's say Hazel survived her illness and got married when she was 21 and got kids a year later at age 22. (we still have 53 years to fill in). Her kids could also have grown up and gotten married at 21 and got kids a year later (31 years left over), which one of them could be Mandus, who could also gotten married when he was 21. We have 10 years left until the events of A Machine For Pigs. His wife appereantly passed away in 1890 when giving birth to the twins, nine years before Pigs.
If Mandus came from Daniel's wife (if he got married), we even have some more years to spare, seeying as we can safely assume Daniel is a few years older than Hazel.