Hi all, thanks for your replies. I don't think Taupau and Aupaau are the same person.
In fact I was given new information, I received an email which provided some information:
"...hannnah wallwork had other children when he went to war,from some man in manono.... Papa's eldest grandchild is Marina then Tommy then Tui...she died in the Tsunami..then there is Eddie and jackie and Rachel....there is John who is Paula's only son and Hilma had no children as she dieD in WW2.... did you know Albert wasnt his first name....he had an older brother...his mother was englsih...he came from Essen and he ended up in Samoa from Heidelberg he was the Architect for Samoa."
All this suggests that Aupaau was not Schaaffhausen's son at all, but the man who took up with Mrs Schaaffhausen while Albert was away at war. I do know that Aupaau was from Manono, and the email above confirms the man Hannah was with was from there.
I was told also told by my family that our grandmother (Aupaau's daughter) was not raised by her mother and only visited her. This makes sense if Mrs Schaaffhausen returned to Albert upon his return from Germany. If it is true that Taupau is not Albert's son, he may be the brother of our grandmother. Her name was Togamau Aupaau.
The descendents of Albert's son Wilhelm (Pupi) maintain Pupi is Albert's only son.
At the Auckland central library they have the Western Samoan films. I was told there are references to two Schaafhausen births, Johnny and Edward - but no years just reference numbers. They were 1282-14 and 1233-14 in that order on that film 1130493 item 1. These may be the children of Pupi referred to above.