This record shows the household in 1910. Both parents were dead, the father the same year as the census. Kristine may be an aunt (father's sister?):

John Olsen 22.04.1858 Osterfjorden hf e Skomagermester S b
Kristine Amundsen 06.09.1869 Florø l tj ug husbestyrerinde (vask etc samt off understøttelse) b
Borghild Amundsen 14.01.1893 Bergen l ug sardinfabrikarbeiderske b
Sverre Amundsen 18.03.1895 Bergen l ug løbergut b
Herman Amundsen 21.11.1897 Bergen l ug fors av nr. 2 b
Alf Amundsen 01.11.1899 Bergen l ug fors av nr. 2 b
Hans Amundsen 23.06.1902 Bergen l ug fors av nr. 2 b

1900 census: Lennebergsmuget 4
Herman Amundsen m b Hf g Blikkenslagersvend 1865 Florø NB n s
Barbra Amundsen k b Hm g Linsøm syerske 1867 Lxsevåg SB n s
Hildur Amundsen k b D ug Datter 1887 t n s
Borghild Amundsen k b D ug Datter 1892 t n s
Sverre Amundsen m b S ug Søn 1895 t n s
Herman Amundsen m b S ug Søn 1897 t n s
Alf Amundsen m b S ug Søn 23111899 t n s


1891 Ytre Markevei 24
Herman Theodor Amunds. M SH G N 66 Florø Herred Blikkenslager Svend
Barbra Elisabeth Dortea Sakariass. K HU G N 67 Laxevaag pr. Bergen
Ragnhild Marie Amunds. K D 990 Nykirkens Bergen By

Bapt. 1890 0911 Nykirken
Ytre Markevei 24
Ragnhild Marie f 0209
Blikmagersvend Herman Thorsteinsen 1865
Barbara Elisabeth Dorthea Sachariasdatter 1867

Bapt. 1893 1202 Domkirken
Borghild Hermanda f 1401
blikkenslager Herman Theodor Amundsen Rosenberggt. 4 1865
Barbra Elisabet Dorthea Sakariassen 1867

You only mention Alf & Hans, do you know what became of the other siblings?

Alf & Hans lived on Gyldenpris, Laksevaag after WW2

I fail to find documentation proving that Amund Torsteinsen had a connection to Dengsrud in Aal?