I have a`few pieces of information about Ulbergs.
Foreigners in Apia; 1880; Peter Uleberg- American
Mr Ulberg, in Samoa pre 1880- H J Moors
Henry Ulberg born 1873 , of DH & PG , Faga, Savaii
manager- Cyclopedia of Samoa 1907
Henry Ulberg- Faga, Savaii, trader; registered halfcaste 1903
Peter Christian Ulberg of Palauli; trader; registered`half caste 1903
Private Frederick Ulberg born 3 April 1890; US WW1 draft- California, mentioned on Samoan War Memorial.
It would appear that Peter Ulberg, an American, came to Samoa pobably about 1870 or maybe earlier, married a Samoan lady, had àt least 2 sons in the 1870s- Peter Christian and Henry.
Frederick is possibly another later son, or a grandson, who went to America.